BoB Mathematical Modeling of Alternative Outcomes

Shortround6 said:

Getting somewhat back on track with the "German" Barges (of the 2400?? collected less than 900 were German)
One discussion board says " Only 860 out of 2,400 barges came from Germany. The invasion barges also came from France (350); and Holland and Belgium (1,200).

we have this photo.
View attachment 606375
and this chart.
View attachment 606376
Obviously there is a huge variation in the barges in size and capability. Barges built to haul coal and iron ore are going to ride high when load with men and military supplies.
Helps when beaching if trimmed by the stern so the soldiers don't have to wade through 1.75 meter water. Helps with reduced flooding with waves coming over the side.
Does increase side area exposed to the wind and reduce the "grip" on the water (cross wind blows the barge sideways easier)

Some of the German Rhine river self propelled barges might well have been able to to do 6kts or better if lightly loaded. However with so many of the barges unpowered the powered ones may have (or may not?) have been tasked with towing one or more unpowered barges. Germans had also collected a number of tug boats for towing duties.

Another photo
View attachment 606377

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They are called "invasion barges" but they are just barges, does anyone know what taking around 2,000 of them off north Europe's waterways did for the economy there? I am sure it was very popular in Belgium and Netherlands, a great way to win friends.

pbehn said:

They are called "invasion barges" but they are just barges, does anyone know what taking around 2,000 of them off north Europe's waterways did for the economy there? I am sure it was very popular in Belgium and Netherlands, a great way to win friends.

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It gets better. A lot were returned to the countries to be shot to pieces by the allied fly boys.

Koopernic said:

... I also suggest an MG42 is an effective weapon against British boats getting within 1200m.

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Might well have been, but as it designation indicates no MG 42s were around in 1940, it began appear in 1942, but MG 34 was the standard GP mg of the Heer in 1940.

Koopernic said:

I suggest a max speed of 18 km/h makes sense, that's 9 knots. So a cruise of 7-8 knots. I suggest soldiers would be high value cargo on powered ships. I think the normal FLAK that accompanied German battalions would be positioned on the barges defensively. I also suggest an MG42 is an effective weapon against British boats getting within 1200m.

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Goodness, over a hundred men, unaccustomed to the sea, seasick and tossed around on flat bottomed barges trying to use their AA cannon and their infantry machine guns whilst running flat out at 9 knots against a flotilla of determinedly-captained RN destroyers does not look like good odds for the Wehrmacht.

Here's the most powerful barge intended for Sealion, the German Siebel artillery support ferry.



Facing each of the few ferries will be a flotilla of RN destroyers.



And what about the regular barges? These poor buggers will never make the beach.

On Siebel ferries Siebel ferry - Wikipedia
How good or poor they were in real life Battle of Sukho Island - Wikipedia
One of their mightiest opponent during the Sukho operation Gunboat "Aunus"

Koopernic said:

I believe the Luftwaffe could have stopped the Royal Navy. Land based bombers supported by land based fighters are too powerful.

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Too powerful? The Germans didn't have that much experience bombing ships - yes, they could do it, Luftwaffe He 111s sank two of the Kriegsmarine destroyers at the beginning of the war, but against the entire Royal Navy? The Home Fleet destroyer squadrons had more destroyers than the Kriegsmarine's entire surface fleet and let's not forget that the 'RAF' is not just 11 Group Fighter Command squadrons, let's remember that 13 Group squadrons were largely out of reach of Bf 109s, so could (and did) operate with impunity against German bombers that ventured that far north. This meant that in the event that 11 Group in the south east couldn't cope, there were other units that could be relied on as back up - something the Germans failed to reconcile with and was the foundation of Park and Dowding's strategy of putting smaller numbers of fighters up at any given time to attack bombers (it worked, by the way). Let's also not forget that German torpedoes in 1940 were terrible and very rarely worked, and the number of torpedo droppers the Luftwaffe had available to it was small in 1940; the Luftwaffe had a total of 135 torpedoes available to it in March 1940, and by the end of September, 1/ Kustenfliegergruppe 106 and its He 115s had fired 16 torpedoes and reported only two hits, which doesn't equate to efficiency, so being realistic, this statement of yours is pure hogwash.

If anyone has any pretensions as to whether Sealion was going to work, here's a quote from one of those involved in its planning and execution, one Heinrich Bartels, who was responsible for assembling the invasion barges at Dunkirk. During a visit by Raeder to the port on the eve of the invasion, he asked Bartels, "Do you think we shall make it across to England? Are you optimistic about it?"

Bartels, slightly taken aback by the questions from his superior, replied with, "Without optimism, Herr Grossadmiral, the thing will be a flop from the start..."

I always like how Derek Robinson got it across in 'A Piece of Cake'.

I used my phone to take snapshots of the relevant pages and used text recognition software to get it in a more presentable form. Any typos are mine.

Quick explanation of characters in the excerpt:

The best way to deal with any military question is this.

***AND THEN IT ALL WENT HORRIBLY WRONG*****

if Sealion goes horribly wrong then you have German soldiers stranded in a barge. And that's called target practice.

If Sealion goes wrong then lordy lordy it is going to be a total humiliation.

German forces and going to be cut off without any resupply on the south coast. Dieppe Landings proved that wisdom.

The charge of the light brigade is a better bet.

Exact borders of the group areas may be subject to debate or changed with time.
Pushing the RAF out of No. 11 Group area (the landing sites) does not mean the RAF has totally disappeared. No 12 Group (even if somewhat depleted) will cover the naval bases on the east coast within easy steaming distance of the invasion sites. No 10 Group is covering both Plymouth and Portsmouth (on the border of No 10 and 11 group).

This map is of fighter command. Bomber command and Coastal Command both still exist.
Granted No 9 and 13 groups may consist of units rebuilding, resting or working up and not at full efficiency.

Best thing the British could have done was let the Germans land 30-60,000 troops, annihilate the Barge fleet that was left and trap the Germans with little food or ammunition along the coastal strip with no way to resupply or evacuate.

A suggestion has been made that the German troops can use their 20mm AA guns and Squad machine guns to defend themselves while in the barges. WIthout being fastened down in some way effective range would be short. Ammunition used in transit would not be available once on the beaches, barges would be defenseless on return trip.
Germans planned on three or more waves or round trips to get all the troops ashore with more trips need for supply.

The Luftwaffe wasn't that much better at sinking ships in Sept/Oct of 1940 than it was in May/June of 1940. RN will take losses in daylight. Losses does not mean being obliterated any more then a the Luftwaffe obliterated the DUnkirk evacuation ships.

Germans would need

Air Supremacy
Sea Supremacy
Time to bombard fixed defences.
Couple of months of good weather.

Invading USSR was considered easier.

So that's a plus.

Just a wee example of how difficult it was for the Luftwaffe to sink shipping in 1940. On the afternoon of 10 July Dornier Do 17s of KG 2, escorted by Bf 110s of III/ZG 76, with Bf 109s from JG 51 high above the formation were sent to destroy a convoy sailing through the Channel, which had been spotted earlier in the day by a Dornier recon aircraft escorted by Bf 109s of I/JG 51, which had been attacked by six Spitfires of 74 Sqn, but managed to return damaged for two Spits damaged by the escorts. At 1pm, the German formation of Do 17s and Bf 110s were detected at 60 plus aircraft by the defences and Flights from three squadrons were sent up to meet them. Attacked from head on, the Do 17 formation was split up and in disarray. By the end of the afternoon, three Bf 110s and three Do 17s were lost and one Bf 109 and pilot lost and one damaged, for the loss of one Hurricane and pilot to the RAF, although four aircraft were damaged. On that afternoon, the RAF achieved a six to one kill ratio, worst of all for the Germans, only one ship in the convoy was hit, despite KG 2 dropping some 160 bombs and even then, the 700 t sloop that sank was empty. Not a good day for the Luftwaffe.

To add to SR6's post above, a breakdown of Fighter Command squadrons as of 1 July 1940 within each Group, illustrating the value that Dowding placed on reserves:

11 Group had a total of 30 squadrons, 8 Spitfire, 17 Hurricane, 5 Blenheim; 12 Group had 11 squadrons, 5 Spitfire, 3 Hurricane, 2 Blenheim and 1 Defiant; 13 Group had a total of 17 squadrons, 6 Spitfire, 9 Hurricane, 1 Blenheim and 1 Defiant. Note that 13 Group's totals are greater than 12 Group's; this is because its squadrons were largely reserves and kept out of harm's way, not to mention the fact that Bf 109s could not reach cities in the North and Scotland from mainland Europe and so the bomber units that operated within 13 Group's area of interest were escorted by Bf 110s only.

Information from Stephen Bungay's The Most Dangerous Enemy (Aurum, 2009).

Koopernic said:

I also suggest an MG42 is an effective weapon against British boats getting within 1200m.

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One of the British 'Boats"


During the war (but not by the summer of 1940) about 800 trawlers were taken into RN service from the Hull and Dovercourt Fisheries. Other areas of The UK also had substantial numbers join the RN

See Trawlers – World War 2 | Harwich & Dovercourt | History, Facts & Photos of Harwich

Not all had 4 in guns.

It was the hundreds of these "boats" available that made Sealion such an impossibility. They were available for minesweeping, mine laying (not very well, anti sub use, and as small gun boats. The Germans did have similar but not in anywhere near the numbers the British did. Much like the larger ships , the Germans are outnumbered by very large amounts.

nuuumannn said:

To add to SR6's post above, a breakdown of Fighter Command squadrons as of 1 July 1940 within each Group, illustrating the value that Dowding placed on reserves:

11 Group had a total of 30 squadrons, 8 Spitfire, 17 Hurricane, 5 Blenheim; 12 Group had 11 squadrons, 5 Spitfire, 3 Hurricane, 2 Blenheim and 1 Defiant; 13 Group had a total of 17 squadrons, 6 Spitfire, 9 Hurricane, 1 Blenheim and 1 Defiant. Note that 13 Group's totals are greater than 12 Group's; this is because its squadrons were largely reserves and kept out of harm's way, not to mention the fact that Bf 109s could not reach cities in the North and Scotland from mainland Europe and so the bomber units that operated within 13 Group's area of interest were escorted by Bf 110s only.

Information from Stephen Bungay's The Most Dangerous Enemy (Aurum, 2009).

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I would have to re read the book, but at some stage Bungay argues that the British created a pilot shortage. "British" being the RAF or Dowding or a combination of all in the organisation. For Dowding and his "Dowding system" a squadron had to exist for his controllers to make use of it. In the worst case scenario, where squadrons are scrambled repeatedly during a day, at the last scramble they must have as close to 12 planes in the air as at the start, if they don't, they are losing. I think Stona posted that in some cases a scrambled squadron was down to 7 planes but that wasn't normal, it is what the LW expected to be normal after just a few days heavy activity. The keeping of reserves was a part of the Dowding system, after each day losses could be compensated for by moving men and machines around, such that the next day the enemy would be confronted with the same in numbers, if not in exact quality. Both Dowding and Park had experience of WW1 aerial warfare and what happens to a squadron when its members were shot down. If you only have 12 aircraft and 12 pilots as a fighting unit you can be lost in a day, just by minor injuries, running out of fuel or getting battle damage and being forced to land somewhere else.

I think the discussion is going a little wrong. It's worth reading the article on operation sealion in Wikipedia on this much as that source is now severely corrupted.

Some facts about the modified barges to invasion barges and river ships (powered barges).
1 They were to be modified by cutting of the bow and attaching a ramp to drive trucks, tanks etc on and off. They also were to have concrete poured in to strengthen floors to handle tanks. Its a fairly daunting amount of modification work.
2 Square bottoms roll less in heavy seas than round. This is not a problem for barges.
3 Unpowered barges after landing tanks were to be marshalled and escorted back to France after 2 days.
4 Unpowered barges could be towed or pushed by either a river ship or the 400 tugs collected for operation sea lion.
5 Over 260 Panzer III and Panzer IV tanks were converted to 'tauchpanzers' or diving tanks. They were sealed and could drive along the ocean floor to a depth of 15m by way of a 16m air intake hose with an radio aerial. Apart from sealing the tanks had bilge pumps and rebreather escape systems for the crew as well as a gyrocompass and navigation system. I don't think these would have been dropped into water that deep, maybe 5m but they would be impervious to fire till they surfaced. They were actually used during operation Barbarossa.
6 The smaller Panzer II modified as a schwimmpanzer (with 20mm canon) would float via way of caissons and fire their gun during their swim ashore.

Dealing with the Royal Navy:
1 The invasion corridor would be cordoned off with a dense mine field from the Royal Navy.
2a Coastal Artillery, based in France, would also cordon of the invasion corridor from the Royal Navy out to much of the distance. The 8.8cm FLAK 37 is a deadly anti shipping weapon due to its fire control and ability to FLAK burst. I imagine 105mm, 6 inch, 8 inch and 11 inch coastal artillery would be set up by the German Navy (who had troops and division for harbour defence). That should protect the invasion fleet half way if not the whole way across the channel in some areas
2b Luftwaffe FLAK 37, FLAK 38 and FLAK 39 8.8 cm, 10.5 com and 12.8 cm guns would be highly effective against shipping and craft.
3 Luftwaffe would have had time to reassess its performance at Dunkirk and change its anti shipping attack methods. We KNOW they became effective. Briefings, notes to crew and a little bit of practice against towed targets. They will learn quickly and they will also be undistracted by campaigns elsewhere.

4 One thing I need to research more is the state of German radar in mid 1940. Seetakt Shipborne radar was definitely available on anything from destroyer up plus a few of the larger torpedo boats. SeeArt (See Artillery) is essentially Seetakt converted for coastal anti shipping use, FuMo 1 Calais A and B and FuMO 2 Calais.

The shore based Seetakt peformed better than ship based because it had a larger antenna, more powerful transmitter and could afford more complicated circuitry that didnt require the same lever of minurisation, marinisation and shock resistance.

This means that a few radar equipped Kriegsmarine ships half way across the channel can detect the Royal Navy and either open fire using night vision optics or illuminate with star shell or search lights while smaller craft attack. The shore based artillery would take care of the rest.

Achieving Air Superiority.

I don't see this as a matter of strategy or tactics by the Luftwaffe. The Luftwaffe didn't have the right equipment.
Required would be the following:
1 All Me 109 and Me 110 equipped with ability to carry a jetisonable fuels tank or a bomb with the necessary modifications to the altimerter (altitude alarm) and Revi Reflector sight (second reticule for the toss angle). The Me 109E4B and Me 109E7B had this facility as the BoB ended and would have been available in fair numbers. It was needed before the BoB stated. The earlier Me 109E1B could carry a bomb but no drop tank. (fixed drop tank for ferrying only)

The additional range should increase penetration depth 60%, it should increase the area of Britain under which the Luftwaffe operated fighters by 2.5 and it should double or treble the number of Luftwaffe fighters over the UK.

2 The Focke-Wulf Fw 187 with DB601 engines and 1300 Litres internal fuel needs to be built, if necessary by sacrificing an equal number of Me 110, around half the force.

It is NOT correct to say that the Fw 187 would not be an excellent dog fighter. Manoeuvrability depends on power to weight ratio of the twin engine aircraft being the same or better than a single fighter. The Fw 187 had that. Wing loading is important but a larger wing may reduce turning circle will also reduce speed so its a trade of.

The Fw 187 would have had far better speed than Me 109, Spitfire and about 65%-70% more range. Likely enough to roam over half of Britain.

3 A high speed reconnaissance aircraft is needed. Either unarmed, unarmoured Me 109 or the Fw 187 to gather intelligence.

RAF losses would be higher, Luftwaffe bomber losses much lower.

Admiral Beez said:

Goodness, over a hundred men, unaccustomed to the sea, seasick and tossed around on flat bottomed barges trying to use their AA cannon and their infantry machine guns whilst running flat out at 9 knots against a flotilla of determinedly-captained RN destroyers does not look like good odds for the Wehrmacht.

Here's the most powerful barge intended for Sealion, the German Siebel artillery support ferry.

View attachment 606451

Facing each of the few ferries will be a flotilla of RN destroyers.

View attachment 606452

And what about the regular barges? These poor buggers will never make the beach.

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That Siebel barge was quite stable and used not only as an armed barge but a landing craft. It was improvised using Army Pontoon Bridge Pontoons and this made it transportable by road an rail, hence it was used in inland lakes and seas and could be used for a river crossing before a pontoon bridge was set up. It could get tiger tanks across a water crossing.




The Siebel Ferrys had a draft of only 1.2m and a little calculation shows that with a 5m ramp (dont know what it actually was) would mean any solider or tank would find himself in 70cm of water assuming a 10:1 beach slope. Fording depth of a Standard Panzer IV at the time was 0.8m latter increased to 1.2 but i imagine special modifications would be made similar to the schwimmpanzer so that fording depth would be ate least half way up the turret.


Noe also the Kommandogeret 40 FLAK predictor. This computed a continuous firing solution so long as the men: the trainer, the layer(elvation) and range finder operator tracked the the targeted enemy ship. If the ship moved the solution would instantly update and the guns would repoint viag their guages If the 'ferry' moved due to swells so long as the layer/trainer maintained track and the fire order was given right it would hit. A RN MTB could be directly targeted by 30-45 rounds per minute of 8.8 cm fire either bursting above them or inside them.

nuuumannn said:

Too powerful? The Germans didn't have that much experience bombing ships - yes, they could do it, Luftwaffe He 111s sank two of the Kriegsmarine destroyers at the beginning of the war, but against the entire Royal Navy? The Home Fleet destroyer squadrons had more destroyers than the Kriegsmarine's entire surface fleet and let's not forget that the 'RAF' is not just 11 Group Fighter Command squadrons, let's remember that 13 Group squadrons were largely out of reach of Bf 109s, so could (and did) operate with impunity against German bombers that ventured that far north. This meant that in the event that 11 Group in the south east couldn't cope, there were other units that could be relied on as back up - something the Germans failed to reconcile with and was the foundation of Park and Dowding's strategy of putting smaller numbers of fighters up at any given time to attack bombers (it worked, by the way). Let's also not forget that German torpedoes in 1940 were terrible and very rarely worked, and the number of torpedo droppers the Luftwaffe had available to it was small in 1940; the Luftwaffe had a total of 135 torpedoes available to it in March 1940, and by the end of September, 1/ Kustenfliegergruppe 106 and its He 115s had fired 16 torpedoes and reported only two hits, which doesn't equate to efficiency, so being realistic, this statement of yours is pure hogwash.

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A Mine corridor and coastal artillery based in France greatly simplifies the problems the German Navy and Luftwaffe would face.

The Luftwaffe was clearly focused on land warfare. The problems at dealing with the Royal Navy evacuation at Dunkirk were clearly used as lessons learned and the Luftwaffe's anti shipping capabillity improved though it took improvements in equipment. It doesn't take much. A few officer would know, the Japanese might provide tips and the training material passed on. Bombs on the Me 109 would help as the 109 was successful of crete as an anti shipping craft. Destroyers are certainly difficult targets.

I suspect the Luftwaffe's main MTB and ship killer would be the Me 110 due to its frontal fire power and heavy bomb load as well as accuracy (as good as the Ju 87 during BoB)

nuuumannn said:

If anyone has any pretensions as to whether Sealion was going to work, here's a quote from one of those involved in its planning and execution, one Heinrich Bartels, who was responsible for assembling the invasion barges at Dunkirk. During a visit by Raeder to the port on the eve of the invasion, he asked Bartels, "Do you think we shall make it across to England? Are you optimistic about it?"

Bartels, slightly taken aback by the questions from his superior, replied with, "Without optimism, Herr Grossadmiral, the thing will be a flop from the start..."

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I worked in Germany in the early 1990s for a year. That's pretty much their sense of humour. It would have been said with a straight face. The laughs at the pub afterward.

The Germans planning operation sealion were intelligent, determined but knew they were up against it. They came up with a plausible plan and when the conditions of the plan were impossible to meet cancelled it.

It should be pointed out that for a nation absurdly accused of planning 'world conquest' the lack of long range aircraft, amphibious craft and the fact that they invaded the Soviet Union knowing they lacked the capability of invading more than 1/4 of the way in (they drew a vertical line to the limit of their logistical and opperational capability, the High Command and Hitler knew) shows something else was going on.

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German attempts for a seaborne invasion of Crete didn't succeed despite the complete absence of RAF or FAA fighters. RN casualties due to shipborne weapons was minimal.

Koopernic said:

3 Unpowered barges after landing tanks were to be marshalled and escorted back to France after 2 days.
.

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The discussion starts to go wrong when statements like this are made. If you believe the Channel is just a wide river the statement will not be challenged. I would like to see a few hundred unpowered barges being marshalled on a shingle beach for 2 or more days in September with a tidal drop of 5 to 7 meters. Repeatedly stating that an aircraft that wasn't built would win the day isn't a convincing argument.