Operation Chastise

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herman1rg

Tech Sergeant
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1,036
Dec 3, 2008
80 years ago today starting at 21:28 19 Avro Lancaster bombers of 617 Squadron RAF took off to attack dams in the Ruhr region of Germany with a unique weapon.
The Mohne and the Eder dams were breached and the Squadron has ever since been known as "The Dambusters"
The RAF lost 53 aircrew killed and 3 captured, with 8 aircraft destroyed.
Two hydroelectric power stations were destroyed and several more damaged. Factories and mines were also damaged and destroyed. An estimated 1,600 civilians – about 600 Germans and 1,000 , mainly Soviet slave labour – were killed by the flooding.
Après moi le déluge
 
80 years ago today starting at 21:28 19 Avro Lancaster bombers of 617 Squadron RAF took off to attack dams in the Ruhr region of Germany with a unique weapon.
The Mohne and the Eder dams were breached and the Squadron has ever since been known as "The Dambusters"
The RAF lost 53 aircrew killed and 3 captured, with 8 aircraft destroyed.
Two hydroelectric power stations were destroyed and several more damaged. Factories and mines were also damaged and destroyed. An estimated 1,600 civilians – about 600 Germans and 1,000 , mainly Soviet slave labour – were killed by the flooding.
Après moi le déluge
Operation Chastise

Almost exactly 80 years ago this British special operation took place, which will be described here. The British head of Bomber Command, General Arthur Harris, let day bombing stay for the time being from the beginning of his term in February 1942. Only one-third of the British bombers hit their targets with their bombs in a circle 8 km in diameter around the target, mainly because of the still intact air defenses. . It was necessary first to leave this waste and herd more defensible bombers, better target sights, and long-range fighters.
The physicist Frederick Lindemann, scientific adviser to the War Cabinet, came up with the idea of nightly large-scale attacks of bomber masses on cities; these would cause such civilian casualties that German fighting morale would very soon collapse. It would cost the British a few dozen bomber crews, but it would cost the Germans the war. It was soon learned that the opposite was more likely to be the case.
Employed by the giant Vickers armaments company was Prof. Barnes Wallis, a sort of Daniel Düsentrieb. He was absolutely peaceable, but by no means a pacifist: an attacked person was allowed to defend himself with hard means. He developed the geodesic design used on the Vickers Wellesley and Wellington.
Also superheavy free-fall bombs weighing several tons, the heavier of which was intended to trigger earthquake waves. (Grand Slam, Tallboy).
He heard from a safe source that 80% of the electricity for the Ruhr and its heavy industry was generated at dam turbines east of it. If these were destroyed, the steelmakers and weapons makers on the Ruhr would be out of action for months. In detail, it was mainly the dams of the Möhne in Westphalia and the Eder in Hessen, but also the smaller ones of the Ennepe, Sorpe and the Lister, not far from the Möhne. Wallis brooded about it for a long time. Some kind of heavy torpedo did not work, since the Germans had placed protective trap nets. Free-fall bombs had no chance at all. Then an idea came to him, inspired by the bouncing on the water of a stone thrown flat and shaped in the same way.
Wallis occupied a technical water channel as an experimental field, much to the displeasure of his colleagues. Using models, he determined the trajectory and speed, bomb size and shape, and much more. And he found something surprising. For the trajectory to fit, the bomb had to be flown very fast and low. The bomb had to decelerate strongly on contact with water and still be able to bounce off. He achieved this with a rounded shape. The bomb had to be large, with quite a thin metal shell. After all, it had to crack a thick stone wall and still be light enough for a powerful carrier aircraft to tow it. It had to hit the dam discreetly after less than 1 km, sink, and go off by pressurized detonator at a depth of 10 meters. So the blast pressure stemmed from the water wall and depressed the dam. That was the idea. It was a very complex problem.

Now it was on to the practical tests. They built some scaled-down prototypes and dropped them off Kent's coast in a Vickers Wellington. The tests were logged and analyzed. Clarifications and modifications were made. It had to be a transverse cylinder rotating against the direction of flight at 500 rpm before dropping for braking to succeed. In order to break down the thick and stable wall, a thick bomb was needed. It had a diameter of 1.25 m, its axis was 1.5 m long. It weighed 4.2 t, 3 t of which was torpex, which has 1.5 times the explosive power of TNT. It had to be dropped at 390 km/h at about 30 m height. That was still 110 m/s in low-level flight, very demanding and close to the Lancaster's maximum performance.

Now the bomb carrier was selected. Because of the bomb mass, it had to be one of the three British Viermots. The choice fell on the AVRO Lancaster for several reasons. It was the only one to have a long, one-piece bomb bay, which allowed a wide variety of loads. In addition, it was fast, maneuverable and easy to control for a large bomber. The bomb bay had to be heavily modified. New test series began and highly skilled volunteer crews were sought.
Guy Gibson, already highly decorated and experienced at age 23, had been chosen as Wing Commander of the 617th Dam Buster Squadron to be created. Gibson was a short man at 5'6", very capable and very difficult. He was arrogant, condescending, and committed to strict discipline. He did not talk to non-commissioned officers and ground presonal. Strict and aloof on the one hand, but on the other audacious to fanatical in pushing through his military goals. He was not a sympathetic choice, but an efficient one. The crews trusted the little creep to bring them to success.

Gibson recruited 20 excellent crews from Lancaster squadrons to volunteer for a high-risk mission. They all wanted to join, had British adventurer mentality. They were aware that a significant number of them would not return. That became the core of the 617th Bomber Squadron, which in the future was to carry out precision attacks with special weapons at high risk.
At first, the crews learned nothing of their tasks. The tests revealed a calculation error: dropped from 30 meters, the roll bomb often burst on impact, and sometimes overshot the target. It was necessary to reduce the dropping height to 18 m, a horrible prospect. There was no measuring device for such low altitudes. But the British promptly invented it, suitable for flat surfaces. It was classic low tech. Two searchlights were mounted on the Lancaster's belly. One under the bow, another just under 10 meters aft. The searchlights were adjusted so that the light cones formed two side-by-side circles at 18 m on the ground, i.e., a horizontal figure eight. The bombardier had to be able to see these through his ground window, which was in the bomber's transparent 'chinstrap'. The bombardier communicated with the pilot during the approach. Now he needed a second tool that would allow him to make a useful estimate of the drop distance of 400 +/- 30 m to the top of the dam. Because in order to function as intended, the bomb had to slap the water surface 3 times, so that the necessary braking effect occurred due to the rotation. The bomb then came to the wall at low speed, and 'crawled' down the wall through the residual rotation until the pressure sensor, set at 9 meters, triggered the fuse.
Wing Cdr Charles Dann of Boscombe Down quickly had an idea. He built a wooden Y. Under the 'trunk' of the Y he made a handle, the two legs could be pivoted and fixed. At the far end of each leg was a white-painted stick. The bombardier held the aiming device with his left hand, on the right he had the drop trigger. The width of the dams was known, so the trigonometry of isosceles triangles could be used to calculate the opening angle for the lateral ends of the dams, and this could then be set on the device. The shooter then had to learn to position his aiming eye correctly, and then the practical exercises could begin. None of this was easy, but they all got it right.
At the Möhne dam, for example, it was particularly easy because it had a distinctive watchtower right on each edge; it was the only one of these dams that was permanently guarded. The opening angle for its dimensions was 28.5°.
For all this, one needed a moonlit night, i.e. full moon +/- 5 days. The outbound and return flights had to be carried out at an altitude of 35 +/-5m, otherwise they would be detected by radar.

During these exercises, the crews were briefed extensively and at length, and the absolute secrecy was clearly pointed out. The target selection now concerned the Möhne, Sorpe, Ennepe, Lister and Eder rivers. The main focus was on the Möhne and Eder. The respective flight paths had been worked out very precisely in order to avoid radar and strong flak positions. The Lancaster B IIIs had been modified: the movable bomb bay doors were omitted, as were the gun turrets at the rear.

Much testing and practicing was done. Then the attack date was set for the night of May 16-17, 1943.
The 19 Lancaster B IIIs took off in 3 waves (9/5/5) from Scampton/Lincolnshire (about 200 km north of London) heading southeast. One crew lost its bearings, another the bomb over the North Sea. 4 planes were shot down on the outward flight, one sustained strafing damage over the Netherlands and had to return; thus 14 Lancasters arrived at their target.

They were greeted with heavy flak at the Möhne. Gibson started, his bomb hitting but not optimally: apparently it had been some distance from the wall. On the next approaches here, Gibson always flew along to draw the flak apart. On the next attempt, the bomb bounced over the top of the wall and the bomber was shot down. Then a drop missed. After that, a bomb hit but didn't cause much damage. The last one, however, was a direct hit. The Möhne dam broke and tremendous amounts of water poured down into the valley.
Three bombers had arrived at the Eder. The first hit but had no effect; the second missed. Again it was the last throw that decided everything.
Only one Lancaster was left for the Sorpe.The bomb hit but did nothing.
There were 3 planes left from the 3rd wave. One headed for the Sorpe and hit, but without effect. A second bomber was headed for the Lister, but the target was not found in the haze. The Ennepetalsperre was hit without visible effect.
On the return flight, another 3 bombers were shot down.

In the Operations Room of Bomber Command the radio traffic also took place; one got to hear everything - how the men fought and also how they died. The high casualties shook Barnes Wallis in particular, who increasingly lost the battle with his tears. He had gotten to know the crews quite well at the briefings before, and now he was suffering.
After the early morning turnaround with bomb loss, the 10 surviving aircraft returned in the morning. Gibson had shown leadership qualities and acted completely fearlessly - this quality sometimes caused him to lose his caution and cost him his life in September 1944. Of the 133 men in the venture, 53 died, a loss rate of 40%. 33 of the 80 survivors were honored by the King.

Tactical consequences.

A 12 m high flood wave rolled down the Möhne. It drowned about 1500 people, 1000 of whom were forced laborers. 330 million liters of water from the Möhne and Eder rivers destroyed houses, factories, roads, mines, railroad tracks as well as bridges. Drinking water production dropped to a quarter for months. The power grid was largely repaired after 6 weeks. The high-loss operation seemed to have yielded little military value, but a psychological one very much so.

Strategic

German coal production fell by a catastrophic 400000 tons in 1943. For the repair work, forced laborers were relocated from the West, who were supposed to build bulwarks against the expected Allied invasion. Thus, the invasion front in northern France was weakened.

The event could also have led to Stalin becoming more aware of the British again - but this was not the case. Stalin was meanwhile pursuing his very own goals, ready to betray the alliance if it seemed to him to be called for. The jubilation of victory in 1945 soon gave way to the shudder of the Cold War.

The Dambuster soldiers fought for themselves, more precisely for their freedom, that is, that of Great Britain. And this was closely connected with the freedom of Europe, which was threatened by the brown brood. One could survive, but also die quite well. Western Europe's regained freedom could also be defended against the Reds from the East, although it got quite close a few times. Thus, Western Europe achieved freedom and peace, as well as economic success like never before. The citizens became older and older and their children more and more spoiled, until an old political sect - modified by green paint - seemed acceptable again and received too much influx. The entitlement attitude and immaturity of their voters made this possible.

At the same time, it would be appropriate - perhaps - to take a look at the Dambusters. They have already earned a little of our gratitude.



View: https://www.youtube.com/watch?v=H1J86UmmI0s

My English is only moderate and meanwhile rusty. So helped deepl.

Pls correct me if I'm wrong.
 

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No copy of the Mohne Dam raid report, where most people were killed, around 1,247 deaths from the raids.

EDER DAM, E. 1679 - Chief, Orpo., 16/17 MAY. This was a low level attack carried out by 3 aircraft which dropped 3 H.E. The resulting damage was 75 metres wide and 20 metres deep. The flow of water through the gap was 2000 cubic metres per second. Electric power from the power station on the Losse was only partially maintained. Trams in Kassel were stopped. By 18 May the water level in Kassel was almost normal. Road traffic was only slightly interrupted. Water supply by 18 May had risen from 50% to 83%. Except for the out for trams and the firm of Henschel (for the latter only for a few hours) the electricity supply was maintained. About 1900 were rendered homeless in Kassel town area.

In Fritzlar water, light and telephone services were interrupted. In the surrounding districts of Fritzlar 3 road and 2 railway bridges were destroyed. Water supply was still interrupted on 19 May. Dorf Affoldern in the Waldeck area was seriously affected. 12 corpses were found. The total stock of food and fodder was destroyed. There were 31 dead in the Waldeck area. The railway line Kassel- Marburg - Frankfurt/Main was cut by the collapse of the Eder Bridge and damage to the railway embankment between Grifte and Wabern. Long distance traffic was diverted and local traffic maintained by bus shuttle service. Total area inundated was about 8500 hectares.

Damage to Buildings:

Kreis Waldeck:
Houses: 42 destroyed, 32 severely damaged, 39 slightly damaged.
Businesses: 60 destroyed, 26 severely damaged, 16 slightly damaged.
Public Buildings: 2 destroyed, 2 severely damaged.

Fritzlar-Homberg;
Houses: 9 destroyed, 9 severely damaged, 79 medium damage, 25 slightly damaged.
Businesses: 2 destroyed, 23 severely damaged, 10 medium damage, 5 slight damaged.

Kreis Melsungen:
Houses: 5 destroyed, 11 severely damaged, 50 medium damage, 264 slightly damaged.
Businesses: 17 destroyed, 7 severely damaged, 24 medium damage, 59 slightly damaged.
Public Buildings: 1 each destroyed, severely damaged, medium damage and slightly damaged.

Landkreis Kassel:
Houses: 1 severely damaged, 29 medium damage, 50 slightly damaged.
Businesses: 1 medium damage, 4 slightly damaged.

Kassel Town:
Houses: 2 destroyed, 63 severely damaged, 193 medium damage, 539 slightly damaged.
Businesses: 1 destroyed, 4 severely damaged, 15 medium damage, 25 slightly damaged.
Public Buildings: 6 medium damage, 2 slightly damaged.

Kreis Hofgeismar:
Houses: 5 severely damaged, 113 medium damage, 233 slightly damaged,
Businesses: 6 destroyed, 40 slightly damaged.
Public Buildings: 5 slightly damaged

Damage to Bridges:
Destroyed: 4 railway, 7 road, 8 wooden.
Severely damaged: 1 railway, 4 road.
Slightly damaged: 1 road.

Loss of Animals etc.: 65 horses, 658 heads cattle, 878 pigs, 475 sheep, 260 goats, 8062 small animals (chickens etc.), 201 swarms of bees.
Casualties (Deaths): Kreis Waldeck: 31, Kreis Fritzlar-Homberg: 16 (incl. 3 foreigners), Kreis Melsungen: 3, Kassel Town: 2, Total 52.

8 OCTOBER, 1943
Wing Commander Gibson led the R.A.F. missions against the Moehne and Eder Dams. In this interview, he tells of the preparations for the mission, and gives some data in reference to the night bombing activities of the R.A.F. over Germany.
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Gentlemen, I am speaking to you as a British bomber command pilot, and what I have to say represents my own ideas and not the combined ideas of all the other bomber command pilots.

I must begin by saying that we in the bomber command have a sort of creed which we must believe in if we do our job - and that is that we could knock Germany out of the war by bombing alone. If we didn't have that creed, we would find it hard to do our work. Bombing Germany by night is an extremely tough and hard job - one which entails very high losses over a long period, although the losses are only about four percent per night.

I might say that the bomber command has only came into its own since the first of January this year, when the Pathfinders made their debut in a big way.

You may be interested to know how these big attacks are organized, as compared to your own VIII Bomber Command in England which is doing great work with its B-24s and Fortresses. Fundamentally, our jobs are vastly different. Whereas, in the VIII Bomber Force missions are against military objectives by precision bombing from high altitude, we go in for devastating areas, the idea being that if there is a ball-bearing factory in Hamburg which is producing a quarter of the ball-bearings required for the German war machine, we will not only break down that ball-bearing factory, but will devastate an area about nine miles around. That will get the houses of the various workmen, other factories, and do untold damage.

The Fortresses, as you know, cannot carry quite the load we can nor fly in such vast numbers over the target. Therefore, their best job is to aim accurately at the targets which we can't get so easily, and thus do a job which is complementary to our night bombing. The Germans have a very powerful fighter force which doesn't drive off the Fortresses, but gives them severe combat. However, German morale must be very low when, having been hit heavily the night before, they see the Fortresses coming over, and again that night there are mere flights. The story of Hamburg, I should think, will live in our memories a long time. That city, which is big indeed - the second largest city in Germany - had a week of almost unknown terror from the air. About 90 percent of the city has been destroyed. The actual press figures are 77 percent, but I say 90 percent because the press figures do not include in the devastated areas those other areas, in between, which are obviously uninhabitable. When you think of 90 percent of a city being destroyed - say, Washington or New York - you can see what a terrific effect it would have on the war effort.

We used to organise our missions over Germany in such a way as to cut down our losses as much as possible. For that reason we would fly in a concentration - not a formation, such as you fly in daylight. To get that picture in your mind, let me take you to a bomber station at 1800 some evening. All the boys will have been briefed: they have been given the target, the time over the target - timing is all that is required. There is no glamor about it and no undue talk. The navigators are the king men in the aircraft. They are the fellows who have to keep their bombers within two miles either side of a track line and within fifteen seconds of the targets. If they are outside that fifteen seconds, tho bomber may be in danger.

About two hours before the rendezvous time all the bombers take off. For morale reasons we try to take off in formation, one as quickly after another as possible, and climb up - with the result that if there is a farm labourer in a field in Lincolnshire, he will be amazed to see 800 bombers overhead, making a noise so loud that he can't hear himself talk. The bombers climb up to about 25,000 feet. About thirty minutes before the time to rendezvous, which be on the coast, or out at sea, the captain will say to the navigator: "Get me a fix". We have - and you have now - an instrument which takes fifteen seconds to get a fix 400 yards accurate. This fix is transmitted immediately onto a chart and the navigator says, "Set a course for the rendezvous point. We will be there in twenty-nine and three-quarter seconds.

From all over Lincolnshire, Suffolk, and Yorkshire, the bombers converge in waves to one point on the coast (or maybe out to sea) and you see all the bombers with their navigation lights on. It is usually getting dark. As soon as they converge the navigation lights go off, and the bomber force is on its way, in the form of a rectangular box. The best way to describe it is to imagine a glass brick full of flies flying along through the air. The sides are about two miles across. In other words, the glass brick is two miles across, about fifteen miles long, 8,000 feet deep, and full of bombers. One after another those waves form and set course for Germany at about 15 minute intervals; sometimes the interval is as much as thirty minutes, and sometimes as short as two minutes, according to the target to be attacked - with the result that a series of hammer blows are delivered on Germany, each carrying something like 700 tons of bombs. If it is a big mission it would heavier perhaps six waves in all, carrying something like 4,000 tons. The Lancaster bomber, which is the standard bomber in our bomber command can carry 18,000 pounds of bombs to the Ruhr, which is a very heavy load.

When they get over the coast line the fight begins. The Germans do everything in their power to stop the bombing attacks. They do it by means of flak and fighters, guided by export radar. You can picture the radar as a round tube on the ground, with a bomber flying along on top. When the bomber goes over, a blip appears on the tube and moves along doing exactly the same thing as the bomber. If, on the other hand, there are 1500 bombers, obviously the whole tube will be covered with blurs. The result is that the guns resort to barrage fire, and the fighters resort to getting into the stream, having a quick squirt at a bomber which doesn't appear on the alert, and then getting out.

On an ordinary mission, such as to Hamburg, you get gunfire from the coast onward, and have to fly through something like an hour of continual gunfire. The density of the guns is quite tremendous and is very, very, frightening. But the point is to remember that no flak shell is likely to bring you down unless it is within forty feet. You may get a flak shell exploding five yards off your wing tip, and making an awful din inside the aircraft and it is frightening - but the losses due to flak, I think, according to statistics, are between one and two percent. That is a loss anyone is prepared to take, similar to the risk you take when crossing a road. There is no evasive action in the bomber command now; they keep their straight flight and course. You got mutual protection by virtue of concentration. Incidentally, the collision risk is very high in turning, so the order of the day is not to turn.

The fighters are a bigger menace. There is a very strong force of them defending the western approaches, and they are controlled by CGI, which becomes completely useless unless there is a straggler. They also have some single-engined fighters operating on moonlight nights. Our rear gunners, copying the American boys now, are extremely offensive indeed. They don't wait, but open fire when they see one coming within the stream. You can always see thirty bombers around you on any of the missions. When these thirty bombers see a fighter they attack, and let him have 120 guns back, with the result they outnumber him by many, many guns. He doesn't like attacking on this basis and goes, to pick off a straggler. That is why our losses are getting lower and lower each day, as our gunners are getting more and more offensive.

When you come to the target, that is where the accuracy of night bombing comes in - accuracy within the limits of the town or city. The Pathfinders, who fly Mosquitos, are equipped to drop bombs accurately on cities.

In an ordinary mission the Mosquitos take off well after the bombers do, being much faster and cruising about 350 m.p.h. Fifteen miles short of the target they drop what is known as a preliminary target bomb, which is a special bomb that bursts at 3,000 feet, with a vivid blue explosion, scattering red, green, or yellow balls which burn on the ground for some minutes. It is a very distinctive bomb indeed, and couldn't possibly be imitated by any dummy or by incendiaries themselves. When the bomb aimers in the first wave see that they say "Right! Good!" They start their stop watches, and begin counting. They then have a pre-determined number of minutes to go to get to the aiming point, which is usually the center of an industrial area.

That is where the morale of the bomber crews has to be high. You hear a fellow counting, saying, "Two minutes to go .....one minute and thirty seconds to go...one minute to go",…..then they begin counting the ten second intervals. For the last five seconds they count each second. All the time the searchlights are coming up around you - collisions, perhaps three or four others may be shot down by fighters. Flares are dropped to illuminate the area. Those seconds take a long time. All are pleased when they hear, "Bombs gone!"

At fifteen seconds they drop the target-indicating bomb, which is the same sort of bomb, only a different colour - maybe green balls bursting on the ground. Then every bomber aims very accurately at these, with the result that tons of bombs go crashing down on the aiming points within thirty seconds, or at the most, two minutes. Incendiaries are in the first wave, accompanied by a few block busters. Ten minutes after that along comes the second wave, with HE only. In the next wave are explosive incendiaries. In the next wave one-hundred-pounders are dropped. And so it goes on, wave after wave, driving hammer blows. The Pathfinder force in Mosquitos are sitting up above, usually led by a group captain or a wing commander, who will say "Good! That aiming point is burning well'. Then they divert the rest of the force to another aiming point some distance away from the first one. The ARP services always reinforce the blitzed part of the cities, so when a part of the bomber force is diverted to another aiming point they usually find a part of the city with no ARP service. That will burn well. The last wave will join up the two, if possible, forming an area of devastation eight miles long and four miles wide.
 
(rest of Guy Gibson statement/interview)
Some of the squadrons, such as mine, perform other types of missions. Most of the chaps are very experienced, and do missions such as the one against the Moehne and Eder Dams. The mission against the dams is a very long story and can never be fully told until after the war, because of certain security aspects.

The Germans built these dams between 1900 and 1911, so I am told, because they thought war would be pretty obvious for the German people in the next twenty-five years and they wanted to have a place to make munitions. The Rhine water is practically undrinkable, because of iron, mainly, and because it runs at such a low level between its banks. Also, it doesn't run through the main industrial area. The only other river is the Ruhr, which is very sweet mountain water. So they dammed up the Moehne Valley and built the Moehne Dam, which is an immense structure. I don't like to compare it with Grand Coulee or Boulder, as they are entirely different types of dams. It is about half a mile across and 150 foot high, and at the bottom of the base, 160 foot, reinforced concrete. At the same time they also know they would need transportation facilities to get their war materials to all points east, so they built the Midland Canal and the Eder Dan, which dams up the Eder River to supply water, in late autumn, and to keep the 'water level in the locks, up to the right height when the canal has to go over mountains.

In the early part of the war our bombers were not able to carry a sufficient weight of bombs to do any damage to those dams.

Many schemes were advanced as possibilities to destroy the dams. Scientists in England were working on a plan to use a big mine which would explode against the wall of the dam, some 40 or 50 foot below the surface, and thus shift the dam back on its base. This needed a lot of study. In January of this year I was taken off the night bomb squadron and told to form my squadron. The Commander in Chief of the R.A.F. said, "You can have priority No.1 in anything you do, and can chose any personnel you like." I looked through all the records and chose-the best pilots and crews in the British Bomber Command.

We had many models made of the dam. They were some feet across, brick for brick the same as Moehne Dam. Little charges the size of a tea cup wore put in the water and the results observed, filmed, and watched in slow motion to see where the crack came and how. Dams were built as wide as this room, again brick for brick the same, and bigger charges were used all over the place to try and find the right position. We found there was only one position, and that was at a certain depth in the water and a certain distance out.

With this information in view, we found out there was a now dam being built in Wales. The old dam, which was high above, was still full of water. So with all the gear and explosives they went up to Wales to actually break down the dam with the theory they had in mind. To their great pleasure and astonishment it worked, and the dam went down, and they knew they had roughly conquered the art of breaking down the dam. But it required a very high degree of precision on the part of the squadron which had to do it. I was given the information that was required. The mines had to be placed within five yards of the exact position in the water. The mine had to be dropped there so as sink, and it had to be within, five yards of that exact spot to work, provided it went off at the right depth. For that reason special and very adequate hydrostatic charges were used.

To do the bombing in daylight would have meant heavy losses, but, on the other hand, the job would have to be done by flying at the right height over the water. You all know at low level have to be at dead accurate height; it is very hard to say "I am now fifty, feet above the water". We chose to do it in the half light of moonlight and dawn mixed.

The flak on the dam was another problem. When the Lancaster is low down its wing span of 105 feet makes it very vulnerable to a few light flak guns firing 37 and 20 mm shells. So the first wave was devised to overcome that. We took out unnecessary gear to make them as light and fast as possible, put on armor, and put in Army-type tracer bullets. The idea was to fire the bombers' guns back to show the gunners on the ground that we were giving them as much as they gave us.

The biggest problem of all in training was to get accuracy. We found we had great difficulty flying at the right height and in dropping the mine from 50 feet exactly, and 235 per hour - nothing more or less. A variance to 225 miles an hour was immaterial, but the height was to be exactly 50 feet. We hung wires out of the aircraft to show when they hit the sea; we put lights on; we used radio altimeters, and found they didn't work. We tried every possible means until someone hit on a very simple solution - a spotlight in front of the aircraft in its nose, and a spotlight on the tail, so arranged that when these two lights converged on the water underneath the aircraft, the aircraft was at 50 foot. You can imagine the navigator on the bombing approach - the pilot had to keep the dam in sight on a special range-finding screen, the bombardier had his sight, and the navigator had his head out the window, looking down, watching the two spotlights converge. "Up ... down … steady". That took a lot of training, and it took up 150 hours of practice to get it right. It took two months.

Mosquitoes were flying over the dam every day, watching the guns to see that they weren't increased. One thing we thought they didn't have – the obvious way to protect a dam - was a cable strung across the valley. If they had put a series of high tension cables across the water, no bomber would have been able to make a low-flying attack. And if you can't make low-flying attacks, you can't bomb dams. You can't photograph cables very well.

As the time went on we were slowly getting proficient until the week came, the one week when you can bomb a dam - 10 May to 20 May in this case. The water was rising up from a level ten feet below to six feet, to four feet - which was the height we wanted it. It had to be four feet on the line to catch the mine if it would overshoot. At the same time we wanted the maximum amount of water in the dam to put it over when the time came.

On the morning of the 16th it became apparent that the water was at the right height, so I told the boys what we were after. We were briefed, and took off a little before midnight on the morning of the 17th. Nine aircraft, led by myself, flow one route, with the other six aircraft on an alternate route. The German RDF can pick you up thirty miles away quite easily, whether you are on the deck or not, so the idea was that the six would act as a diversion for the nine. We would carry out the main job of bombing the Moehne Dam, and the six wore going to bomb the Sorpe Dam, which is not as important and doesn't contain half as much water.

The six got a little off course and crossed the Dutch coast in an area which is very heavily defended. There was a gap there of about 200 yards where there were no guns. That is where they meant to go, but they missed it and two of them got shot. Another fellow had to take evasive action and hit the sea.

My nine came straight across and picked up the canal. We had to navigate extremely accurately, because there were thousands of guns and searchlights all the way around there. It was case of navigating from the white house to a big tree, from the big tree to a pond. We finally got up the Rhine and there we were picked up by searchlights very badly. It was then about 2.30 in morning. A big glow was beginning to appear in the Northern sky, and there was a full moon. At last we arrived over the clam.

We were told that the gunners n the dam were all home guard, men who never had first a shot in the war. The original plan of action when we arrived over the hill was to stream across the dam and beat it up with the guns, thus making, the home guard man so frightened they wouldn't fire on us. However, we found the gunners were very good indeed and were putting up quite a little party for us. We were all equipped with radio telephones, so we decided we wouldn't beat it up, but would attack.

After a certain amount of time in getting the right landmarks, I went in and made my approach. My bomb man did a good job, and dropped the mines on the right spot. They were very heavy, weighing 9,000 pounds each, of which 6,000 pounds was an explosive of a type of which you probably haven't heard, probably the highest explosive in the world. When they blow up, a terrific column of water - about a thousand feet - shot up over the wall of the dam, and a hundred yards behind the tail, which shook the rear gunner. A great wave kept right on down the reservoir and we had to hold up No.2's attack until it became perfectly calm again. That took ten minutes.

He came in and dropped his mines right. Then he was shot down by light flak on the dam, and fell about a mile, beyond. Once again there was a terrific water spout and waves went up and down.

Ten minutes after that No.3 came in. He attacked and the wall of the dam shifted on its axis about five or ten feet - it didn't leak, it just shifted. There was a highway on the top of the dam which you could see.

No.4 came in, forty minutes after the first attack. He attacked and got shot down, but the wall of the dam rolled over backwards on its axis. It had moved back a little each time, and fifth the final blow it went over, and the water came out.

There were 134,000,000 tons of water there. It was getting light then and I saw it going down the valley. It appeared to be a wave something like 75 feet high. I saw cars down the valley with the headlights on, trying to drive out. Then I saw the water go over the cars, and finally the headlights going out - down past villages and railway yards. I stayed just to see the full column of water go out, and having seen that I radioed back to base the word "Big!" which meant that the Moehne Dam had collapsed. Air Marshal Harris was there, and he notified the Prime Minister in Washington. There was a nation wipe hook-up on that one word.

Then we went on to the Eder Dam. That was an attack by two aircraft - two Australian chaps. The water rolled down the valley, and went on down to the town of Kassel, where it caused serious damage by flooding, apart from doing immense damage to the big aerodromes, underground hangars, equipment and the service personnel, which was a good thing, from a war point of view.
----------
(The above is a copy of Command Informational Intelligence Series No.43 - 131 issued by Assistant Chief of Air Staff (Intelligence) Washington).
(Reproduced from RAAF OPERATIONAL INFORMATION BULLETIN - 57/43. dated 14 December 1943).
 
Operation Chastise

Almost exactly 80 years ago this British special operation took place, which will be described here. The British head of Bomber Command, General Arthur Harris, let day bombing stay for the time being from the beginning of his term in February 1942. Only one-third of the British bombers hit their targets with their bombs in a circle 8 km in diameter around the target, mainly because of the still intact air defenses. . It was necessary first to leave this waste and herd more defensible bombers, better target sights, and long-range fighters.
The physicist Frederick Lindemann, scientific adviser to the War Cabinet, came up with the idea of nightly large-scale attacks of bomber masses on cities; these would cause such civilian casualties that German fighting morale would very soon collapse. It would cost the British a few dozen bomber crews, but it would cost the Germans the war. It was soon learned that the opposite was more likely to be the case.
Employed by the giant Vickers armaments company was Prof. Barnes Wallis, a sort of Daniel Düsentrieb. He was absolutely peaceable, but by no means a pacifist: an attacked person was allowed to defend himself with hard means. He developed the geodesic design used on the Vickers Wellesley and Wellington.
Also superheavy free-fall bombs weighing several tons, the heavier of which was intended to trigger earthquake waves. (Grand Slam, Tallboy).
He heard from a safe source that 80% of the electricity for the Ruhr and its heavy industry was generated at dam turbines east of it. If these were destroyed, the steelmakers and weapons makers on the Ruhr would be out of action for months. In detail, it was mainly the dams of the Möhne in Westphalia and the Eder in Hessen, but also the smaller ones of the Ennepe, Sorpe and the Lister, not far from the Möhne. Wallis brooded about it for a long time. Some kind of heavy torpedo did not work, since the Germans had placed protective trap nets. Free-fall bombs had no chance at all. Then an idea came to him, inspired by the bouncing on the water of a stone thrown flat and shaped in the same way.
Wallis occupied a technical water channel as an experimental field, much to the displeasure of his colleagues. Using models, he determined the trajectory and speed, bomb size and shape, and much more. And he found something surprising. For the trajectory to fit, the bomb had to be flown very fast and low. The bomb had to decelerate strongly on contact with water and still be able to bounce off. He achieved this with a rounded shape. The bomb had to be large, with quite a thin metal shell. After all, it had to crack a thick stone wall and still be light enough for a powerful carrier aircraft to tow it. It had to hit the dam discreetly after less than 1 km, sink, and go off by pressurized detonator at a depth of 10 meters. So the blast pressure stemmed from the water wall and depressed the dam. That was the idea. It was a very complex problem.

Now it was on to the practical tests. They built some scaled-down prototypes and dropped them off Kent's coast in a Vickers Wellington. The tests were logged and analyzed. Clarifications and modifications were made. It had to be a transverse cylinder rotating against the direction of flight at 500 rpm before dropping for braking to succeed. In order to break down the thick and stable wall, a thick bomb was needed. It had a diameter of 1.25 m, its axis was 1.5 m long. It weighed 4.2 t, 3 t of which was torpex, which has 1.5 times the explosive power of TNT. It had to be dropped at 390 km/h at about 30 m height. That was still 110 m/s in low-level flight, very demanding and close to the Lancaster's maximum performance.

Now the bomb carrier was selected. Because of the bomb mass, it had to be one of the three British Viermots. The choice fell on the AVRO Lancaster for several reasons. It was the only one to have a long, one-piece bomb bay, which allowed a wide variety of loads. In addition, it was fast, maneuverable and easy to control for a large bomber. The bomb bay had to be heavily modified. New test series began and highly skilled volunteer crews were sought.
Guy Gibson, already highly decorated and experienced at age 23, had been chosen as Wing Commander of the 617th Dam Buster Squadron to be created. Gibson was a short man at 5'6", very capable and very difficult. He was arrogant, condescending, and committed to strict discipline. He did not talk to non-commissioned officers and ground presonal. Strict and aloof on the one hand, but on the other audacious to fanatical in pushing through his military goals. He was not a sympathetic choice, but an efficient one. The crews trusted the little creep to bring them to success.

Gibson recruited 20 excellent crews from Lancaster squadrons to volunteer for a high-risk mission. They all wanted to join, had British adventurer mentality. They were aware that a significant number of them would not return. That became the core of the 617th Bomber Squadron, which in the future was to carry out precision attacks with special weapons at high risk.
At first, the crews learned nothing of their tasks. The tests revealed a calculation error: dropped from 30 meters, the roll bomb often burst on impact, and sometimes overshot the target. It was necessary to reduce the dropping height to 18 m, a horrible prospect. There was no measuring device for such low altitudes. But the British promptly invented it, suitable for flat surfaces. It was classic low tech. Two searchlights were mounted on the Lancaster's belly. One under the bow, another just under 10 meters aft. The searchlights were adjusted so that the light cones formed two side-by-side circles at 18 m on the ground, i.e., a horizontal figure eight. The bombardier had to be able to see these through his ground window, which was in the bomber's transparent 'chinstrap'. The bombardier communicated with the pilot during the approach. Nowhe needed a second tool that would allow him to make a useful estimate of the drop distance of 400 +/- 30 m to the top of the dam. Because in order to function as intended, the bomb had to slap the water surface 3 times, so that the necessary braking effect occurred due to the rotation. The bomb then came to the wall at low speed, and 'crawled' down the wall through the residual rotation until the pressure sensor, set at 9 meters, triggered the fuse.
Wing Cdr Charles Dann of Boscombe Down quickly had an idea. He built a wooden Y. Under the 'trunk' of the Y he made a handle, the two legs could be pivoted and fixed. At the far end of each leg was a white-painted stick. The bombardier held the aiming device with his left hand, on the right he had the drop trigger. The width of the dams was known, so the trigonometry of isosceles triangles could be used to calculate the opening angle for the lateral ends of the dams, and this could then be set on the device. The shooter then had to learn to position his aiming eye correctly, and then the practical exercises could begin. None of this was easy, but they all got it right.
At the Möhne dam, for example, it was particularly easy because it had a distinctive watchtower right on each edge; it was the only one of these dams that was permanently guarded. The opening angle for its dimensions was 28.5°.
For all this, one needed a moonlit night, i.e. full moon +/- 5 days. The outbound and return flights had to be carried out at an altitude of 35 +/-5m, otherwise they would be detected by radar.

During these exercises, the crews were briefed extensively and at length, and the absolute secrecy was clearly pointed out. The target selection now concerned the Möhne, Sorpe, Ennepe, Lister and Eder rivers. The main focus was on the Möhne and Eder. The respective flight paths had been worked out very precisely in order to avoid radar and strong flak positions. The Lancaster B IIIs had been modified: the movable bomb bay doors were omitted, as were the gun turrets at the rear.

Much testing and practicing was done. Then the attack date was set for the night of May 16-17, 1943.
The 19 Lancaster B IIIs took off in 3 waves (9/5/5) from Scampton/Lincolnshire (about 200 km north of London) heading southeast. One crew lost its bearings, another the bomb over the North Sea. 4 planes were shot down on the outward flight, one sustained strafing damage over the Netherlands and had to return; thus 14 Lancasters arrived at their target.

They were greeted with heavy flak at the Möhne. Gibson started, his bomb hitting but not optimally: apparently it had been some distance from the wall. On the next approaches here, Gibson always flew along to draw the flak apart. On the next attempt, the bomb bounced over the top of the wall and the bomber was shot down. Then a drop missed. After that, a bomb hit but didn't cause much damage. The last one, however, was a direct hit. The Möhne dam broke and tremendous amounts of water poured down into the valley.
Three bombers had arrived at the Eder. The first hit but had no effect; the second missed. Again it was the last throw that decided everything.
Only one Lancaster was left for the Sorpe.The bomb hit but did nothing.
There were 3 planes left from the 3rd wave. One headed for the Sorpe and hit, but without effect. A second bomber was headed for the Lister, but the target was not found in the haze. The Ennepetalsperre was hit without visible effect.
On the return flight, another 3 bombers were shot down.

In the Operations Room of Bomber Command the radio traffic also took place; one got to hear everything - how the men fought and also how they died. The high casualties shook Barnes Wallis in particular, who increasingly lost the battle with his tears. He had gotten to know the crews quite well at the briefings before, and now he was suffering.
After the early morning turnaround with bomb loss, the 10 surviving aircraft returned in the morning. Gibson had shown leadership qualities and acted completely fearlessly - this quality sometimes caused him to lose his caution and cost him his life in September 1944. Of the 133 men in the venture, 53 died, a loss rate of 40%. 33 of the 80 survivors were honored by the King.

Tactical consequences.

A 12 m high flood wave rolled down the Möhne. It drowned about 1500 people, 1000 of whom were forced laborers. 330 million liters of water from the Möhne and Eder rivers destroyed houses, factories, roads, mines, railroad tracks as well as bridges. Drinking water production dropped to a quarter for months. The power grid was largely repaired after 6 weeks. The high-loss operation seemed to have yielded little military value, but a psychological one very much so.

Strategic

German coal production fell by a catastrophic 400000 tons in 1943. For the repair work, forced laborers were relocated from the West, who were supposed to build bulwarks against the expected Allied invasion. Thus, the invasion front in northern France was weakened.

The event could also have led to Stalin becoming more aware of the British again - but this was not the case. Stalin was meanwhile pursuing his very own goals, ready to betray the alliance if it seemed to him to be called for. The jubilation of victory in 1945 soon gave way to the shudder of the Cold War.

The Dambuster soldiers fought for themselves, more precisely for their freedom, that is, that of Great Britain. And this was closely connected with the freedom of Europe, which was threatened by the brown brood. One could survive, but also die quite well. Western Europe's regained freedom could also be defended against the Reds from the East, although it got quite close a few times. Thus, Western Europe achieved freedom and peace, as well as economic success like never before. The citizens became older and older and their children more and more spoiled, until an old political sect - modified by green paint - seemed acceptable again and received too much influx. The entitlement attitude and immaturity of their voters made this possible.

At the same time, it would be appropriate - perhaps - to take a look at the Dambusters. They have already earned a little of our gratitude.



View: https://www.youtube.com/watch?v=H1J86UmmI0s

My English is only moderate and meanwhile rusty. So helped deepl.

Pls correct me if I'm wrong.

Contrary to the popular mythology about 617 squadron, the crews were not all recruited by Gibson personally and not all were volunteers. From "A Hell of a Bomb" by Stephen Flower

"The film [The Dambusters] has since given the impression that Gibson had a free hand to choose his crews from the whole of Bomber Command, with many well decorated and 'tour -expired' crews volunteering, bringing with them a wealth of experience. The reality was different. His choice was restricted to 5 Group and men were posted in regardless of whether they had volunteered or not. He did not know all the pilots, not all the crew members were decorated and some had not even finished one tour, let alone two. Some of them were 'posted across the station' from 57 squadron, including its entire C Flight, despite protests."

The 57 squadron ORB laments losing 5 "experienced" crews to 617 squadron on 26 March 1943. The book then goes on:-

"The reasons for joining were as varied as the men themselves. Some had an offer made to them and took it up because it sounded interesting, or saw it as a means of remaining with crewmates they already knew and trusted. The hard-bitten types who, like their new CO, preferred to remain in the front line, looked on it as a means of avoiding the instructing duties that they would normally have been given after finishing a tour. Others arrived with a certain sense of grievance, such as Sgt Stefan Oancia, the bomb aimer in Flt Sgt Ken Brown's Anglo American crew, who later commented that he did not recall volunteering for this transfer."

Dave Shannon was one of those wanting to stay on ops and had served with Gibson in 106 squadron. P/O Warner Ottley DFC arranged the transfer of his crew to 617. Gibson asked for and got MIck Martin as he had met him and knew he was a low flying expert. While Gibson's own crew were experienced only his wireless operator had flown with him before.

The use of the spotlights to determine height was the invention of Benjamin Lockspeiser, MAP Director of Scientific Research, and not Gibson, as portrayed in the movie, visiting a show in London. As noted by Geoff, the spotlights were monitored by the navigator through the blister on the starboard side of the cockpit canopy. The bomb aimer was too busy doing his thing. More recent research has shown that the beams were not perfect sometimes converging below the surface (IIRC especially if the surface was flat calm).

As for the bomb sight described above not all the crews chose to use it. The problem was that the bomb aimer tended to get shaken about. With one hand on the sight and one on the bomb release switch some found they couldn't hold it steady. 3 of the crews allocated to the Eder chose an alternative. Chinagraph vertical lines on the bomb aimers blister and strings from that held to their nose. They could then hold whemselves steady on both elbows. The two that successfully bombed the Eder put their accuracy down to the different method.

So a great deal of co-ordination was required between the navigator, watching the height, the bomb aimer, checking the distance and line to the target, and the pilot flying the aircraft. Any error by one of these crew members could result in the bomb not going where it should.

The last of the 20 aircraft (19 for the op plus a spare which had been used for the trials) did not arrive until the day of the raid.

The attack technique needed for the Sorpe dam was entirely different due to its different construction. Unlike the masonry Mohne & Eder dams, the Sorpe had a concrete core with sloping earth banks either side. So the attack had to be made along the length of the dam with the bomb being dropped unspun, hopefully to roll down the side and explode in the water. To add to the difficulty the valley in which it sat was heavily covered in mist on the night.

Of the last wave of 5 aircraft, two were shot down en route to the target, one brought its bomb home after being unable to find the Sorpe dam, one bombed the Sorpe after several attempts and one unsuccessfully bombed what was thought to be the Ennerpe dam but post-war was found to be the Bever dam.

The other lesser known "bouncing bomb" was Highball, small enough to be carrried two at a time in a suitably converted Mosquito. These aircraft feature in much footage taken in 1943 and 1944 of the trials undertaken in Loch Striven. Another squadron, 618, was formed on 1 April 1943 with the intention that they should be used against German warships should they venture out to sea. As this proved unlikely, the squadron was dispersed later in 1943, some of the crews being used to operate the Mosquito Mk.XVIII with the 6pdr gun. In mid-1944 the plans were dusted off with the intention of using the weapon against Japanese warships with the Mosquitos launched from aircraft carriers. Crews were taught how to deck land a Mosquito and the squadron was sent out to Australia at the end of Oct 1944. The weapon was never used operationally however.
 
Contrary to the popular mythology about 617 squadron, the crews were not all recruited by Gibson personally and not all were volunteers. From "A Hell of a Bomb" by Stephen Flower

"The film [The Dambusters] has since given the impression that Gibson had a free hand to choose his crews from the whole of Bomber Command, with many well decorated and 'tour -expired' crews volunteering, bringing with them a wealth of experience. The reality was different. His choice was restricted to 5 Group and men were posted in regardless of whether they had volunteered or not. He did not know all the pilots, not all the crew members were decorated and some had not even finished one tour, let alone two. Some of them were 'posted across the station' from 57 squadron, including its entire C Flight, despite protests."

The 57 squadron ORB laments losing 5 "experienced" crews to 617 squadron on 26 March 1943. The book then goes on:-

"The reasons for joining were as varied as the men themselves. Some had an offer made to them and took it up because it sounded interesting, or saw it as a means of remaining with crewmates they already knew and trusted. The hard-bitten types who, like their new CO, preferred to remain in the front line, looked on it as a means of avoiding the instructing duties that they would normally have been given after finishing a tour. Others arrived with a certain sense of grievance, such as Sgt Stefan Oancia, the bomb aimer in Flt Sgt Ken Brown's Anglo American crew, who later commented that he did not recall volunteering for this transfer."

Dave Shannon was one of those wanting to stay on ops and had served with Gibson in 106 squadron. P/O Warner Ottley DFC arranged the transfer of his crew to 617. Gibson asked for and got MIck Martin as he had met him and knew he was a low flying expert. While Gibson's own crew were experienced only his wireless operator had flown with him before.

The use of the spotlights to determine height was the invention of Benjamin Lockspeiser, MAP Director of Scientific Research, and not Gibson, as portrayed in the movie, visiting a show in London. As noted by Geoff, the spotlights were monitored by the navigator through the blister on the starboard side of the cockpit canopy. The bomb aimer was too busy doing his thing. More recent research has shown that the beams were not perfect sometimes converging below the surface (IIRC especially if the surface was flat calm).

As for the bomb sight described above not all the crews chose to use it. The problem was that the bomb aimer tended to get shaken about. With one hand on the sight and one on the bomb release switch some found they couldn't hold it steady. 3 of the crews allocated to the Eder chose an alternative. Chinagraph vertical lines on the bomb aimers blister and strings from that held to their nose. They could then hold whemselves steady on both elbows. The two that successfully bombed the Eder put their accuracy down to the different method.

So a great deal of co-ordination was required between the navigator, watching the height, the bomb aimer, checking the distance and line to the target, and the pilot flying the aircraft. Any error by one of these crew members could result in the bomb not going where it should.

The last of the 20 aircraft (19 for the op plus a spare which had been used for the trials) did not arrive until the day of the raid.

The attack technique needed for the Sorpe dam was entirely different due to its different construction. Unlike the masonry Mohne & Eder dams, the Sorpe had a concrete core with sloping earth banks either side. So the attack had to be made along the length of the dam with the bomb being dropped unspun, hopefully to roll down the side and explode in the water. To add to the difficulty the valley in which it sat was heavily covered in mist on the night.

Of the last wave of 5 aircraft, two were shot down en route to the target, one brought its bomb home after being unable to find the Sorpe dam, one bombed the Sorpe after several attempts and one unsuccessfully bombed what was thought to be the Ennerpe dam but post-war was found to be the Bever dam.

The other lesser known "bouncing bomb" was Highball, small enough to be carrried two at a time in a suitably converted Mosquito. These aircraft feature in much footage taken in 1943 and 1944 of the trials undertaken in Loch Striven. Another squadron, 618, was formed on 1 April 1943 with the intention that they should be used against German warships should they venture out to sea. As this proved unlikely, the squadron was dispersed later in 1943, some of the crews being used to operate the Mosquito Mk.XVIII with the 6pdr gun. In mid-1944 the plans were dusted off with the intention of using the weapon against Japanese warships with the Mosquitos launched from aircraft carriers. Crews were taught how to deck land a Mosquito and the squadron was sent out to Australia at the end of Oct 1944. The weapon was never used operationally however.
Thank you. This is how a post turns into a nice detailed discussion, factual and friendly. It does not get any better than this.
 
Just pickng up something EwenS said about 618 squadron and the Highball mini-bouncing bomb. I don't think it was envisaged using it against German capital ships at sea. The aim was to attack them in harbour, specifically the Tirpitz. Depending on which fijord it was lurking in range was a huge problem making it virtually a suicide mission as there was no prospect of a return flight. One option considered was to bomb then fly on to a Russian airfield unannounced. For reasons of secrecy the Air Staff were unwilling to warn the Russians. Imagine the reception as a bunch of twin-engined aircraft overfly the base. JU88s anyone? Fortunately the idea was eventually binned but only after extensive training and awful stress on the crews.
 
Just pickng up something EwenS said about 618 squadron and the Highball mini-bouncing bomb. I don't think it was envisaged using it against German capital ships at sea. The aim was to attack them in harbour, specifically the Tirpitz. Depending on which fijord it was lurking in range was a huge problem making it virtually a suicide mission as there was no prospect of a return flight. One option considered was to bomb then fly on to a Russian airfield unannounced. For reasons of secrecy the Air Staff were unwilling to warn the Russians. Imagine the reception as a bunch of twin-engined aircraft overfly the base. JU88s anyone? Fortunately the idea was eventually binned but only after extensive training and awful stress on the crews.
From Nov 1942 when Highball had first been considered, a range of targets were looked at and rejected for one reason or another.

Tirpitz is the one that stands out because it progressed furthest. Operation Servant was conceived to strike Tirpitz in Kaafjord in Norway from a Russian airfield. That was finally scrapped because firstly the chances of success were deemed to be low, because even operating from Russian airfields, it was at the extreme limits of the Mosquito's range. And with heavy German fighter cover in the area, and so much of the route over enemy territory, losses were expected to be high. This operation was also in competition with Operation Source, the attack by midget submarines (X-craft) which went ahead in Sept 1943 and succeeded in putting Tirpitz out of action for 6 months. This was before all the kinks in using Highball had been worked out.

Other targets considered included:-
Attacks on northern German ports from Britain. Only Trondheim & Kiel were within range.
Inland waterways in Europe
U-boat bunkers but only Brest was deemed feasible
Locks at St Nazaire and La Pallice allowing U-boats access to the sea.
Against beach obstacles in support of amphibious landings
Rothensee Ship Lift in Germany linking various canal systems in Germany
Italian Navy ships

Most importantly there was a document dated 28 Feb 1943 issued by the Air Staff ( PRO AIR 6-63) and quoted by Des Curtis DFC, a member of 618 squadron, in his book "A Most Secret Squadron" which is worth repeating (with my emphasis):-

"Appreciation of the Relative Priorities to be accorded to the Mosquito and Lancaster Spherical Bomb Projects.

Weapons:- The spherical bomb for the Mosquito, which will carry two, weighs 950 lbs. It has a charge weight of about 600 lbs, a diameter of 35 inches, and is launched at low level with a back spin of approximately 500 r.p.m. The range will be about three quarters of a mile. The weapon is intended primarily for:-

i. the attack of the Tirpitz when protected by booms
ii. the attack of major naval units and other shipping at sea."


After the Tirpitz operation was dropped AVM Slessor, CinC Coastal Command, proposed using 618 and Highball against U-boats coming out of the Baltic & using the Faroe Channel to access the Atlantic. Wallis himself certainly believed the weapon capable of open sea use. In Aug 1943 open sea trials were run off Wick. It is not clear if the two things were linked as the level of secrecy applied to the whole venture meant not everything was fully noted in squadron ORBs.

Highball was also tested from April 1943 against an "armoured wall" on the Ashley Walk bombing range in the New Forest (i.e on land). There is film footage of these trials floating about on the net. That was followed by a series of trials in Oct 1943, intended to test its potential use against railway tunnels in northern Italy. The GWR provided a disused tunnel at Maenclochog near Haverfordwest. So the storyline for the 1969 movie "Mosquito Squadron" starring David McCallum does have some small element of truth behind it.

It was June 1944 before Highball was seen as a reliable weapon however.

The target ships used in Loch Striven for the trials were:-

Courbet - a French battleship, but RN manned, previously used as a Free French depot and administration ship at Portsmouth. Used April - Dec 1943. She was later sunk as part of one of the Gooseberry breakwaters off Normandy.

Malaya - an old British battleship used May-Sept 1944.

Then, with a Mosquito having been landed on the carrier Indefatigable on 25 March 1944, thoughts turned to carrier operations. Due to the weight of the Mosquito & the deck strength required of the carriers, only Implacable & Indefatigable were suitable platforms. So more modifications to the aircraft, 618 brought up to full strength and more Highball training, as well as deck landing training, before, at the end of Oct, it was packed onto the escort carriers Fencer & Striker at Glasgow docks and sent off to Australia where it languished untl 29 June 1945 when it disbanded, the Highballs themselves being destroyed by deliberate explosion the following month.

In Spring 1944 the Japanese caused a panic by transferring the bulk of their fleet to the Singapore / Dutch East Indies area. Various Allied redeployments of ships and aircraft were made between Feb and May 1944, which coincides with plans to resurrect 618 squadron for use in the Far East. Then of course there was the Battle of the Philippine Sea in June and the various battles around the Philippines in Oct that reduced the Japanese Fleet significantly. But it was mid-Nov before the remaining Japanese battleships left the DEI for home leaving only a few cruisers and smaller vessels.

When first proposed in Nov 1942 the Beaufort was under consideration as a suitable Highball carrier. I've also come across an official document asking for Admiralty consideration as to whether the Beaufort could be flown of a carrier (presumeably the answer was in the negative). Trials were also undertaken with 2 Grumman Avengers fitted with Highball in 1943/44 but there doesn't seem to be any indication of intended use.

There was also a larger version of Highball, 4ft diameter with a 750lb charge. 4 to be carried in a Wellington and 6 in a Warwick. It was later discarded.
 
From Nov 1942 when Highball had first been considered, a range of targets were looked at and rejected for one reason or another.

Tirpitz is the one that stands out because it progressed furthest. Operation Servant was conceived to strike Tirpitz in Kaafjord in Norway from a Russian airfield. That was finally scrapped because firstly the chances of success were deemed to be low, because even operating from Russian airfields, it was at the extreme limits of the Mosquito's range. And with heavy German fighter cover in the area, and so much of the route over enemy territory, losses were expected to be high. This operation was also in competition with Operation Source, the attack by midget submarines (X-craft) which went ahead in Sept 1943 and succeeded in putting Tirpitz out of action for 6 months. This was before all the kinks in using Highball had been worked out.

Other targets considered included:-
Attacks on northern German ports from Britain. Only Trondheim & Kiel were within range.
Inland waterways in Europe
U-boat bunkers but only Brest was deemed feasible
Locks at St Nazaire and La Pallice allowing U-boats access to the sea.
Against beach obstacles in support of amphibious landings
Rothensee Ship Lift in Germany linking various canal systems in Germany
Italian Navy ships

Most importantly there was a document dated 28 Feb 1943 issued by the Air Staff ( PRO AIR 6-63) and quoted by Des Curtis DFC, a member of 618 squadron, in his book "A Most Secret Squadron" which is worth repeating (with my emphasis):-

"Appreciation of the Relative Priorities to be accorded to the Mosquito and Lancaster Spherical Bomb Projects.

Weapons:- The spherical bomb for the Mosquito, which will carry two, weighs 950 lbs. It has a charge weight of about 600 lbs, a diameter of 35 inches, and is launched at low level with a back spin of approximately 500 r.p.m. The range will be about three quarters of a mile. The weapon is intended primarily for:-

i. the attack of the Tirpitz when protected by booms
ii. the attack of major naval units and other shipping at sea."


After the Tirpitz operation was dropped AVM Slessor, CinC Coastal Command, proposed using 618 and Highball against U-boats coming out of the Baltic & using the Faroe Channel to access the Atlantic. Wallis himself certainly believed the weapon capable of open sea use. In Aug 1943 open sea trials were run off Wick. It is not clear if the two things were linked as the level of secrecy applied to the whole venture meant not everything was fully noted in squadron ORBs.

Highball was also tested from April 1943 against an "armoured wall" on the Ashley Walk bombing range in the New Forest (i.e on land). There is film footage of these trials floating about on the net. That was followed by a series of trials in Oct 1943, intended to test its potential use against railway tunnels in northern Italy. The GWR provided a disused tunnel at Maenclochog near Haverfordwest. So the storyline for the 1969 movie "Mosquito Squadron" starring David McCallum does have some small element of truth behind it.

It was June 1944 before Highball was seen as a reliable weapon however.

The target ships used in Loch Striven for the trials were:-

Courbet - a French battleship, but RN manned, previously used as a Free French depot and administration ship at Portsmouth. Used April - Dec 1943. She was later sunk as part of one of the Gooseberry breakwaters off Normandy.

Malaya - an old British battleship used May-Sept 1944.

Then, with a Mosquito having been landed on the carrier Indefatigable on 25 March 1944, thoughts turned to carrier operations. Due to the weight of the Mosquito & the deck strength required of the carriers, only Implacable & Indefatigable were suitable platforms. So more modifications to the aircraft, 618 brought up to full strength and more Highball training, as well as deck landing training, before, at the end of Oct, it was packed onto the escort carriers Fencer & Striker at Glasgow docks and sent off to Australia where it languished untl 29 June 1945 when it disbanded, the Highballs themselves being destroyed by deliberate explosion the following month.

In Spring 1944 the Japanese caused a panic by transferring the bulk of their fleet to the Singapore / Dutch East Indies area. Various Allied redeployments of ships and aircraft were made between Feb and May 1944, which coincides with plans to resurrect 618 squadron for use in the Far East. Then of course there was the Battle of the Philippine Sea in June and the various battles around the Philippines in Oct that reduced the Japanese Fleet significantly. But it was mid-Nov before the remaining Japanese battleships left the DEI for home leaving only a few cruisers and smaller vessels.

When first proposed in Nov 1942 the Beaufort was under consideration as a suitable Highball carrier. I've also come across an official document asking for Admiralty consideration as to whether the Beaufort could be flown of a carrier (presumeably the answer was in the negative). Trials were also undertaken with 2 Grumman Avengers fitted with Highball in 1943/44 but there doesn't seem to be any indication of intended use.

There was also a larger version of Highball, 4ft diameter with a 750lb charge. 4 to be carried in a Wellington and 6 in a Warwick. It was later discarded.
I have the book, which is very good, but had not spotted any reference to Highball use at open sea. Thanks for highlighting that. I am surprised it would be effective but need to go back and check its characteristics more carefully.
 
Tremendous discussion, chaps.
I'll just add that when I was studying Morse Code for my First Class Scout rank, I detected an anomaly in the US TV version. The code name for success against Mohne was "The N Word" (later internet complications were shortened to GGD, for Guy Gibson's Dog) but clearly the radio operator heard dash dot at first rather dash...
 
There is an interesting article in the June 2023 edition of "Aeroplane" magazine titled "Against the Odds. Sorpe dam raid".

The 1943 Operation order for "Chastise" identified the Sorpe dam as the second most important target after the Mohne, of the 6 dams listed. Accordingly the whole of the second wave of 5 aircraft to be led by Joe McCarthy were allocated to attack it. It was hoped that some spare bombs would be left over from the first wave of 9 aircraft which could also be used against the Sorpe. McCarthy remembered Wallis saying it would need 4-6 bombs to do sufficient damage to the water side of the dam's sloping stone facing to allow enough water through to erode the material between it and the dam's concrete core which would, hopefully, have suffered minor cracks. Destroying it would be more of a slow burn that the spectacular results achieved at the Mohne & Eder.

The attack method involved attacking along the length of the dam rather than at right angles to it. The bombs would be upspun. They would simply hit the water, sink and roll down until the hydrostatic pistols reach the appropriate depth to explode them. The attack was made more difficult by the terrain around the dam, principally the 300m hills at each end and a church steeple.

The crews allocated to the Sorpe maintained that, until the briefing on 16 May, they had no idea of the different attack method required nor had they trained for it, despite subsequent comments that they were "specially trained crews".

Of the 5 aircraft in the second wave only McCarthy's reached the Sorpe. One lost its bomb after flying too low and hitting the sea. Another suffered flak damage crossing the enemy coast and turned back. The remaining pair were shot down before reaching the target.

McCarthy was in many ways lucky. Scheduled to lead the second wave, his aircraft went U/S and the crew had to transfer to the spare. So, being over half an hour late taking off, they chose a separate route from the other 4 aircraft.

McCarthy's bomb aimer was Johnny Johnson, who was the last surviving original aircrew member of 617 when he died in Dec 2022. Such was the difficulty in setting up the bomb run, he was only satisfied enough to drop the bomb on attempt no 10!

As I noted previously, 1 aircraft from the third, reserve, wave also made it to the Sorpe that night. It dropped its bomb on the 6th attempt.

Subsequent German reports revealed that both bombs exploded about 30m apart and 3m under the surface. Reports of damage vary from 12m deep to 8m in diameter and 4-5m deep. While the top of the dam suffered some minor damage, as shown in subsequent aerial photos, the core remained intact with the service tunnel through it displaying no sign of leakage.

So despite being designated as the second most important target that night it was the one least suited to being targeted by the "Upkeep" bomb. Who knows, maybe if "Tallboy" had been available sooner (or even better "Grand Slam" if it could have been carried that far) they would have proven better suited to destroying the Sorpe.
 
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So despite being designated as the second most important target that night it was the one least suited to being targeted by the "Upkeep" bomb. Who knows, maybe if "Tallboy" had been available sooner (or even better "Grand Slam" if it could have been carried that far) they would have proven better suited to destroying the Sorpe.

In addition to that, Speer in his memoir expressed surprise at how the RAF never bombed the other two dams while they were being repaired, which of course would have caused setbacks to those efforts.
 
So despite being designated as the second most important target that night it was the one least suited to being targeted by the "Upkeep" bomb. Who knows, maybe if "Tallboy" had been available sooner (or even better "Grand Slam" if it could have been carried that far) they would have proven better suited to destroying the Sorpe.
Hi
The Sorpe Dam was attacked by No. 617 Sqn. using 12 Tallboy bombs on 15 October 1944 from 13,000 to 15,000 feet, one failed to go off and there were two direct hits and some near misses. The dam was not breached but did leak. Image below from page 144 of 'Bombs Gone' by Macbean and Hogben:
Image_20230523_0001.jpg

Mike
 
What kind of fuze was used in the spherical bombs?
Hi
Both UPKEEP and HIGHBALL used a modified Hydrostatic Pistol Mk. XIV, three of them in the former weapon, these were programmed to function at a depth of 30 feet. Basically like depth charges.

Mike
 
So - in use against ships, Highball was expected to slam into the ship's hull, bounce off, sink, then explode? I guess they wouldn't work unless under water then. If on land or stuck on a ship's superstructure - it wouldn't detonate?
 
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