If the RAF had been defeated in the Battle of Britain

The knowledge of drop zones didn't have impact on naval battles on the tactical level. The info on convoys made the interception more certain but the radar equipped RN task forces had patrolled north of Crete already during the previous night. And the battle shows the effects of the warships versus a lightly protected convoy if the warships made contact with the convoy. IIRC correctly Kriegsmarine ciphers were still fairy secure at that time. The ships transported Heer's troops (Mountain troops of the 5th Mountain Div). I cannot remember how much inroads into Heer ciphers British had made at that time. The weak point of German signal security were the LW ciphers and the LW many times babble out also KM's and Heer's secrets in its messages. The other possibility was Italian ciphers as the escort ship was an Italian Spica-class torpedo boat (Lupo) and IIRC Brits read the Italian naval codes at least periodically during the war. So yes, on 21 May, as the result of Sigint info, an a/c from Egypt (a Maryland of No. 39 Sqn) sighted convoys of caiques escorted by warships allowing the RN to attack the first convoy around midnight 21/22 May. The second convoy skirmish happened during the morning of 22 May while the RN ships were under heavy and effective air attacks.

The allied troops on Crete (3 British battalions, 2 New Zealanders Brigades, 8 Greek Battalions and 6 Australian Battalions) had been aware of the impending assault through Enigma intercepts, and by a process of deduction were able to accurately estimate the drop zones for the attacking german forces. However the allied commanders on the spot were not provided with any details as to the strengths or actual landing zones of the German airborne forces. The allied forces on the spot worked this out on their own initiative.

The Germans had been provided with inaccurate intelligence and dropped into stiff resistance of nearly three times the amount of men they were expecting. Pure and simple this was a mistake on their part. They stuffed up through faulty intel. The garrison had been re-enforced by allied troops who had retreated from the Greek mainland. In most of the drops they were sitting targets.

The allies had no knowledge at all of the amphibious or seaborne intervention forces. These forces were not using the cracked enigma codes. they were either using the as yet unbroken 5 rotor version of the code, or the never broken Italian naval ciphers. Moreover whilst some low grade information information was being hacked into and the LW blabbing like a squawking baby which gave a good deal of information on some element of the german plan, the naval forces patrolling around crete were not so blessed with fore knowledge of the invasion forces. Again it is worth noting that the commanders on the spot were denied any access to intel of this nature, the sensitivity of the intelligence was simply too great to allow this to be widely distributed

There was no such thing as the Battle of Britain. What there was was a Campaign by the Luftwaffe against The RAF and RN and latter British Munitions manufacturing targets and associated infrastructure. There could be no decisive battle, such as the Battle of Hastings, that could lead to collapse of the British Government and takeover of territory.

The simple reality is that there was no significant German preparation for a war with Britain. Their solution was to defeat Britain's Allie France so that Britain lacked the bases to prosecute a war against Germany.

But what preparations could have been taken with the stretched resources they had? Id say insufficient.

For instance if the simple expedient of fitting drop tanks (a technology known and used by the Luftwaffe on its He 51 over Spain) to all Bf 109E and Bf 110C had of been taken then probably the Luftwaffe might have achieved levels of attrition that meant that the RAF would loose air superiority and thus allow the Luftwaffe to operate its bombers with acceptable losses over only about 50% of Britain. Even with drop tanks there was insufficient range to reach all of the UK and Britain could simply move its vital factories and RAF training bases out of range in the Western Half.

After the Norwegian campaign there was no German Surface Navy left. That's one reason the German aircraft carrier Graf Zeppelin {edit correct from Spey} was suspended: there was nothing left to escort it properly and nothing in sight. I think they were down to 4 destroyers.

The major reason was faulty u-boat Torpedoes which Admiral Doenitz had calculated would have lead to 37 sinkings of Royal Navy ships had they had worked. The faults were:
1 the depth keeping mechanism became faulty because the reference pressure chamber leaked air from ambient. Exercises had failed to consider the long periods submarines would actually spend under water in actual combat. As a result the torpedoes ran too deep.
2 The magnetic proximity fuse didn't work properly.
3 the contact pistol trigger also didn't work.
So the u-boats had torpedoes that ran far too deep and had both magnetic and contact pistol that didn't work.

The problem was quickly fixed, much faster than the US navy fixed a similar problem, but the opportunity to seriously deteriorate the Royal Navy while protecting the Kriegsmarine's own surface ships was lost. The Kriegsmarine must defeat the RN at Narvick.

In order for even a remote chance of a German invasion you need the following pre conditions. These are only the realistic ones.

1 German Torpedoes worked in Norway Campaign thereby keeping German Navy intact.

2 All Me Bf 109 and Bf 110 are all fitted with drop tanks prior to so called Battle of Britain.
3 The first flight of the Focke Wulf Fw 187 is allowed with Daimler Benz DB 600/601 or Jumo 211 in 1938 instead of the impossibly undersized Jumo 210 so that perhaps a hundred of these long range escort fighters are operational by BoB start 1940. The Fw 187 flew with inferior and undersized Jumo 210 because the Bf 110 and Ju 87 had priority. This allows the Luftwaffe to escort over the entirely of Britain with a fighter competitive with Spitfires and Hurricanes. This can easily be achieved by compromising Me 110 production in favor of Fw 187 production.

The above might check mate the RAF.

4 The German Navy needs many more u-boats, perhaps twice is many blockade Britain and occupy the RN. They only had 36 u-boats at the outset of War. Perhaps the Graf Spey or the H class battleships could be abandoned, maybe even Bismarck and Tirpitz to find the steel.
5 A proper long range maritime reconnaissance bomber to support the u-boats instead of the fragile and under armed Fw 200 airliner. Ju 89 could have done the job. It would need to be available in larger numbers.
6 Long range escorts and patrols to protect the u-boats. See Fw 187. A proper fighter version of the Ju 88 instead of the bomber versions that had their bomb sight replaced with a 20mm canon. The majority of Ju 88 patrolling the bay of Biscay were Ju 88A series and they were not aqueduct to the task.
7 The British armies at Dunkirk must be captured or destroyed. The German Army must attack and take losses instead of allowing the Luftwaffe to try and do the job.

So its August 1940 merely through better torpedoes, fitting drop tanks, Abandoning Fw 190 development and some Bf 110 production in favour of a long range escort:
1 German Bombers can range over most of Britain with painful but sustainable losses because Spitfire production and fighter pilot losses can't keep up.

2 The Luftwaffe and u-boats can keep the invasion zone clear of the RN and it's Stukas can support the invasion.

But there are no amphibious landing craft. The Luftwaffe Transport units and it's pilots are decimated due to Dutch FLAK so there is no way of getting there. Sure the Giant Me 321 and 321 might support the job but they aren't ready either.

The German Navy has some superb landing aircraft in design or construction but they can't be ready by the fall of 1940 and a landing in the weather of say Jan 1941 sounds difficult.

I also have no surety of the state of British Army radar which is responsible for coastal artillery. Chain Home is to primitive for fire control but Chain Home Low came out of UK Army work for coastal artillery.

Furthermore there is a looming Soviet danger.

The relevant anti invasion activity off Crete ive previously summarized in the "This Day in the War In Europe"

At 2330 on the 21st NE of Canea, the convoy being led by RM LUPO convoy was attacked by CLA DIDO, CL AJAX, and ORION and DDs KIMBERLEY, HASTY, HEREWARD, and JANUS of Force D. The bow of cruiser AJAX was bent through ramming a caique. ORION sustained some damage to her bridge from pom pom fire from DIDO. Two men were killed and nine were wounded. DIDO expended 70% of her ammunition, CL ORION 62%, and AJAX 58%.

Ten schooners (FI 5000 grt (est)) were sunk by the British ships. Steamer CARMEN SYLVA (Ru 1601 grt) was also sunk.

RM TB LUPO was hit by 18 six inch shells but incredibly survived despite heavy damage. The action was broken off at 0400/22nd. RM TB LIRA rescued some of LUPO convoy survivors.

Force B CLs GLOUCESTER and FIJI with DDs GRIFFIN and GREYHOUND, returning from an uneventful sweep through Matapan Strait, was bombed for 1.5 hrs from 0630 as it was returning to join Force A-1. GLOUCESTER received some splinter damage from near misses. Cruiser FIJI received slight hull damage from near misses. GLOUCESTER only had 18% of her AA ammunition remaining. Cruiser FIJI only had 30% remaining. Force B joined Force A 1 at 0830.

British Force C, composed of CLAs NAIAD, CALCUTTA and CARLISLE, and RAN CL PERTH, as well as DDs KANDAHAR, KINGSTON, and NUBIAN attacked the RM convoy being escorted by TB SAGITTARIO. Torpedo boat SAGITTARIO was hit several times and at least one caique was set on fire. However the attack was broken off due to air attacks. The force withdrew to the SW, but was hampered in that CARLISLE's maximum speed was only twenty one knots, due to various defects.

CLA NAIAD sustained four near misses and her speed was limited to 16 knots. Two of her turrets were knocked out. The damage was structural. 7 men were killed and 31 wounded. NAIAD was able to proceed to Alexandria arriving on the 23rd.

CLA CARLISLE was hit on the bridge by a bomb and badly damaged. The skipper was killed. The cruiser was also struck by a second bomb. 15 crew were killed and 25 were wounded. The cruiser was repaired at Port Said from 26 May to 20 June.

DD KINGSTON closed to take off survivors from cruiser CARLISLE, but was ordered away. The cruiser was able to continue unassisted. KINGSTON was damaged by a near miss which caused damage to her machinery and hull. One rating was killed and two were wounded on the DD.

RAN CL PERTH was damaged by a near miss which damaged her six inch fire control. She sustained no personnel casualties. The cruiser arrived at Alexandria on the 23rd.

Force C joined Force A 1 at 1500. The German air attacks continued. BB WARSPITE was hit by a bomb at 1332 that put her starboard 4" and 6" batteries out of action. Her speed was reduced to 18 knots. Commissioned Boatswain A. E. Harding and seven ratings were killed, twenty four were missing, eleven died of wounds, and sixty nine were wounded. The BB arrived at Alexandria on the 24th. On 25 June, BB WARSPITE departed Alexandria for repairs at Bremerton, Washington. The BB departed Honolulu on 4 August and arrived at Esquimalt on 10 August escorted by two Canadian warships. She departed that day, under US.escort, for Bremerton, arriving on 11 August. Repairs were completed on 18 December 1941.

BB VALIANT was struck by two bombs aft that caused no serious damage or any personnel casualties.

At about noon, GHI Class DD GREYHOUND (RN 1350 grt) was detached to sink a caique, sighted by BB WARSPITE, between Pori and Antikithera. The DD sank the caique, but then was sunk herself by bombing while rejoining the Fleet. 76 officers and crew were lost with the ship. A further 8 crew were killed while in the water when strafed by attacking Me 109s. Some of the crew ended up on Crete, where 4 ratings were make POWs

What followed was a major blow for the RN. HMS GLOUCESTER formed part of a naval force acting against Axis military transports that themselves were trying desperately to get reinforcements to the hard pressed paratroopes fighting for Maleme airfield. The force began in operations nth of Crete with some success. On 22 May 1941, while in the Kythera, about 14 mi nth of Crete, she was attacked by LW Ju87s and sank, having sustained at least four heavy bomb hits and three near-misses. Of the 807 men aboard at the time of her sinking, only 85 survived. Her sinking is considered to be one of Britain's worst wartime naval disasters.

DDs KANDAHAR and KINGSTON picked up survivors. KINGSTON was damaged by near misses of air bombs. CLs FIJI and GLOUCESTER were ordered to support DDs KANDAHAR and KINGSTON.

On 30 May 1941, in a letter to the First sea Lord Dudley Pound, Admiral Cunningham wrote, "The sending back of GLOUCESTER and FIJI to the GREYHOUND was another grave error and cost us those two ships. They were practically out of ammunition but even had they been full up I think they would have gone. The CO of FILI told me that the air over GLOUCESTER was black with planes"

Cunningham was determined, though, that the "navy must not let the army down". At about this time of these heavy losses when army generals feared he would lose too many ships, Cunningham famously said, "It takes the Navy three years to build a destroyer. It takes 300 years to build a tradition. The evacuation will continue"

Colony Class CL FIJI (RN 8530 grt) was sunk at 1830 by the LW. DDs KANDAHAR and KINGSTON dropped rafts and left the area, returning after dark to rescue survivors. KINGSTON picked up 339 survivors and KANDAHAR picked up 184. There were 523 survivors of the 780 man crew.

Colony Class CL FIJI in company with GLOUCESTER, returning to join Force C, came under heavy air attack at 1550. Town Class CL GLOUCESTER (RN 9400 grt) was hit by bombs and sunk. Cruiser FIJI dropped rafts for the survivors and continued with DDs KANDAHAR and KINGSTON.

DDs KANDAHAR and KINGSTON were able to refuel from the battleships in Force A 1.

RAN DDs STUART, VOYAGER, and VENDETTA coming from Alexandria were also ordered to pick up FIJI survivors, but they were unable to locate any. DDs KELLY, KASHMIR, KIPLING, KELVIN, and JACKAL from Malta joined Force A 1 later on the 22nd. At 1930, the DDs were detached to search of survivors of CLs GLOUCESTER and FIJI.

DDs DECOY and HERO were detached from Force A-1 to pick up the King of Greece, the Greek Prime Minister, and other important personages at Suda Bay.

Commando ship GLENROY with 900 troops departed Alexandria for Tymbaki escorted by CLA COVENTRY and sloops AUCKLAND and FLAMINGO. They were ordered at 2335 on the 23rd to return to Alexandria.

DDs JAGUAR and DEFENDER with ammunition for the troops on Crete departed Alexandria and joined Force A-1 off Crete. The DDs were detached to Suda Bay at 2359 on the 23rd.

CA YORK was abandoned after further damage by the LW.


22 May 1941
During the night of 22/23 May in Crete operations, DD DECOY picked up the King of Greece and his party from Crete. DD HERO in company picked up other important persons. Both DDs rejoined Force A-1 on the 23rd. The DDs were sent on ahead later on the 23rd.
DDs KELLY, KASHMIR, and KIPLING were on patrol in the Canea Bay area. DD KIPLING experienced a steering defects and withdrew to the west to correct it. DDs JACKAL and KELVIN patrolled in Kissamo Bay without event and returned to Force A-1 at dawn. DDs JERVIS, RAN NIZAM, ILEX, and HAVOCK patrolled Heraklion.
CLs ORION and AJAX were to join, but were unable to rendezvous in time and returned to Force D
DD ILEX was damaged by a near miss from the LW during the morning of 23 May. There was damage to her propeller, but sustained no personnel casualties. DD HAVOCK was near missed by the LW with damage to the boiler room. 15 men were killed and 10 were wounded. Force E arrived at Alexandria at 2000/23rd.

Enigma Decrypts "Ultra" were never used without a cover story ie "plausible deniability". Patrols or reconnaissance missions would have been set up in either a random or regular pattern so as to prevent German intelligence getting a correlation between compromised signals and allied actions.

Assets were however positioned whether they were patrols, battleships or fleets to take advantage of the foreknowledge Ultra provided. Field commanders were given orders not so general that they were unprepared. In Crete allied commander prepared for airborne assault. Patrols detected ships and assets just happened to be close enough to intervene.

The human tendency to be triumphant and to gloat or discredit a defeated enemy usually contradicts itself when viewed transcendentally. For instance one can not claim that the Germans were incompetent at protecting their ciphers by making it so easy yet be proud of how these "difficult" ciphers and their valuable information were cracked by allied ingenuity. One can not value Ultra yet at the same time be disparaging of German strategies or tactics because one wants them to seem fools associated with a bad ideology or because one does not want allied troops with the advantage of Ultra not to receive credit for their victory because they were playing with the advantage of a loaded dice. One can not have ones cake and eat it too.

As the Europe that the victorious allies inherited disappears in the way that it wanted and history for the most part becomes a lurid Hollywood version we must get the history true because few of the new peoples who inherit this posterity will care either way. The best we can hope for is they respect our truth.

German airborne operations against Holland were not compromised by any Enigma decrypts, and they too were very nearly a disaster. In terms of valuable transport aircraft and crews lost they were, and definitely limited German options against Britain.

It was the first large scale airborne landing in history and though lessons may have been learned the very idea that the Germans could have launched anything better a few months later across the English Channel is a ridiculous as much of the rest of Sealion planning. They planned to do the very thing in the capture of Lympne airfield that officers involved in the Dutch operation cautioned against! The pictures of burning Ju 52s littering various Dutch airfields should have concentrated the minds of the planners.

I recommend 'The Battle For The Hague -1940' by Lieutenant Colonel E. H. Brongers (ISBN: 9789059113077) for a good account of the airborne operations against Holland.

Cheers

Steve

One of the weaknesses of the German Navy, worsened when u-boat wolf packs started, was that they were sometimes prone to being chatty. Radio can be detected and the transmitter located.

Ultra changed during the war, like most things. The number of messages that could be decoded in a day or week increased by a huge amount from beginning to end. Most histories (which could be wrong) put the effective start of British code breaking as June of 1941, I am sure some efforts were going on before then, but results may have been much lower. What commanders in the field knew is another thing.

Graph is for the average number of Ultra dispatches to field commanders per day.
By the end of the war field commanders did have a significant advantage in knowing German plans. In 1940 and early 1941, not anywhere near as much.
And the actual content/detail is also important. A warning from Ultra that the Germans plan to send an invasion convoy to Crete is a big assist, giving the number of ships, the course the expected time of arrival would have been a much bigger assist. Of course most any commander worthy of the name knew where the most likely ports for such a convoy to come from were, what course (with a few zig zags ) they would have to come on, and roughly what hours they would come (night with arrival near dawn to minimize exposure) so allied commanders were not lead by the hand by Ultra.

Enigma was neither one type of machine, nor one code.

In 1940 the British could decipher a significant part of Luftwaffe traffic (mainly due to lax operational procedures) and some Army traffic, but none for the Kriegsmarine. All the services were using a version of the Enigma I, the KM's M3 machine was based on this, but Luftwaffe and Army machines were supplied with five cipher wheels, the Naval versions eight. Any more detail of how they were used you can look up yourselves

The breakthrough in deciphering naval traffic came in mid 1941, when the British worked out the wiring of the additional wheels, and most popular accounts of enigma (Imitation Game etc.) give the impression that this was THE breaking of enigma, which is not the case.

On 2nd February 1942 the KM introduced a new enigma machine (the M4). This machine added an extra wheel which added an additional stage to the cryptographic algorithm. The extra wheel was not moved during encypherment and could not be exchanged with the other three wheels. The British were once again locked out of naval traffic, not regaining access until NINE MONTHS later.

Some versions of enigma, like the Enigma K used by the Abwehr, were never routinely broken, in fact it was never really broken at all.

Cheers

Steve

I am reliably informed by the BBC that Turing decoded all enigma traffic filled in the the Times crossword then did a round of golf before lunch.

Koopernic said:

For instance if the simple expedient of fitting drop tanks (a technology known and used by the Luftwaffe on its He 51 over Spain) to all Bf 109E and Bf 110C had of been taken then probably the Luftwaffe might have achieved levels of attrition that meant that the RAF would loose air superiority and thus allow the Luftwaffe to operate its bombers with acceptable losses over only about 50% of Britain. Even with drop tanks there was insufficient range to reach all of the UK and Britain could simply move its vital factories and RAF training bases out of range in the Western Half.

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The training bases could be moved, the factories not so much. At least not in a few weeks.
Deeper penetrations would also lead to higher German losses. For incoming raids Radar told the British they were coming and told them the course over the channel (which could change over land) once 100-200 miles into Britain the British would know where they are and would know what route they would have to take to get out of Britain.
Please note that a lot of the early raids were right along the coast and the Germans could be over water in minutes if not, in some cases , seconds.

After the Norwegian campaign there was no German Surface Navy left. That's one reason the German aircraft carrier Graf Spey was suspended: there was nothing left to escort it properly and nothing in sight. I think they were down to 4 destroyers.

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I believe the carrier was the Graf Zeppelin, the Graf Spee was the Panzerschiff sunk off Montevideo. The Germans may very well have been down to 4 destroyers in June of 1940 but in the fall they were up to at least 7 with another 2-3 soon to be repaired?

The problem was quickly fixed, much faster than the US navy fixed a similar problem, but the opportunity to seriously deteriorate the Royal Navy while protecting the Kriegsmarine's own surface ships was lost. The Kriegsmarine must defeat the RN at Narvick.

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The last was not going to happen. And I would note that British submarines caused a substantial amount of damage to German heavy vessels even if they did not sink them.

In order for even a remote chance of a German invasion you need the following pre conditions. These are only the realistic ones.

1 German Torpedoes worked in Norway Campaign thereby keeping German Navy intact.

2 All Me Bf 109 and Bf 110 are all fitted with drop tanks prior to so called Battle of Britain.
3 The first flight of the Focke Wulf Fw 187 is allowed with Daimler Benz DB 600/601 or Jumo 211 in 1938 instead of the impossibly undersized Jumo 210 so that perhaps a hundred of these long range escort fighters are operational by BoB start 1940. The Fw 187 flew with inferior and undersized Jumo 210 because the Bf 110 and Ju 87 had priority. This allows the Luftwaffe to escort over the entirely of Britain with a fighter competitive with Spitfires and Hurricanes. This can easily be achieved by compromising Me 110 production in favor of Fw 187 production.

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1. even with the best torpedoes in the world the U-boats could not have saved the Scharnhorst from getting hit by a torpedo from a destroyer unless you think the U-boats could have swept the Norwegian coast of all British surface ships. Commander of the Glorious should have shot for stupidity had he lived. Gneisenau among other misadventures was hit by a torpedo from HMS Clyde on June 20th which put here out of action for 5 months. Karlsruhe was sunk by the HMS Truant. Leipzig and Nurnberg had both missed the Norwegian campaign due to torpedo damage suffered in Dec 1939 From British subs.
U-boats weren't going to save the Blucher either unless better torpedoes could take out shore batteries.
2. covered above.
3. There was nothing wrong with flying the initial FW 187s with Jumo 210s. either 1/4 or 1/3 of the Bf 110s used in Poland used Jumo 210s due to the shortage of DB 601 engines. Perhaps the mistake was in not shifting over later, but the whole evaporative cooling system scheme also delayed development of the FW 187 . I would also note that NO service Ju 87 used a DB 601 engine so they cannot be blamed for the FW 187 not getting them.

4 The German Navy needs many more u-boats, perhaps twice is many blockade Britain and occupy the RN. They only had 36 u-boats at the outset of War. Perhaps the Graf Spey or the H class battleships could be abandoned, maybe even Bismarck and Tirpitz to find the steel.
5 A proper long range maritime reconnaissance bomber to support the u-boats instead of the fragile and under armed Fw 200 airliner. Ju 89 could have done the job. It would need to be available in larger numbers.
6 Long range escorts and patrols to protect the u-boats. See Fw 187. A proper fighter version of the Ju 88 instead of the bomber versions that had their bomb sight replaced with a 20mm canon. The majority of Ju 88 patrolling the bay of Biscay were Ju 88A series and they were not aqueduct to the task.
7 The British armies at Dunkirk must be captured or destroyed. The German Army must attack and take losses instead of allowing the Luftwaffe to try and do the job.

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4. most sources say the Germans had 56-57 U-boats at the start of the war. How many were ready for sea may be different. Many are the small type IIs but that is the size you want if actually trying to operate in the channel or british coastal waters. I don't know how many more they got in service in teh year leading up to Sea lion.

Stopping production of large surface ships means the British have time to change their building plans. I would also note that something under 2000 tons of steel had been assembled at the docks for the first two H class ships when construction was stopped so that doesn't get you much in the way of U-boats. Assuming of course that the steel is even suitable for U-boats and doesn't have to be sent back , melted down and reworked. Scrapping the Bismark and Tirpitz before completion means an awful lot of wasted money in already completed engines and armament (H class guns were used in shore batteries) and could very well signal to the British that they don't need five King George Vs??

more later.

Parachute and glider assault is a surprise tactic, it only works for as long as measures are not taken. During the BoB RAF pilots who had to make a forced landing had to be very carefull near the south coast because so many fields were filled with poles and other obstacles.

A lot of ditches, with a resulting bank several feet high, were dug across potential landing grounds as a fast, effective and cheap means of deterring gliders. The ditches could also subsequently be filled in causing little trouble to the landowner, always a consideration in a democracy!
Cheers
Steve

I'm as confident as I can be that the Germans wouldn't have been able to launch a surprise invasion. The invasion force was too slow, the UK radar would have picked them up and the ports were under close PR surveillance.
I'd certainly concede that the Enigma codes were broken less frequently in 1940 but the defences were ready. All RAF bases were reasonably well defended against parachute troops and some difficult decisions made. For example all AA guns had to be capable of firing against ground targets. It made them more vulnerable against air attack as the walls were a lot lower, but the benefit was a much stronger defence.

stona said:

Enigma was neither one type of machine, nor one code.

In 1940 the British could decipher a significant part of Luftwaffe traffic (mainly due to lax operational procedures) and some Army traffic, but none for the Kriegsmarine. All the services were using a version of the Enigma I, the KM's M3 machine was based on this, but Luftwaffe and Army machines were supplied with five cipher wheels, the Naval versions eight. Any more detail of how they were used you can look up yourselves

The breakthrough in deciphering naval traffic came in mid 1941, when the British worked out the wiring of the additional wheels, and most popular accounts of enigma (Imitation Game etc.) give the impression that this was THE breaking of enigma, which is not the case.

On 2nd February 1942 the KM introduced a new enigma machine (the M4). This machine added an extra wheel which added an additional stage to the cryptographic algorithm. The extra wheel was not moved during encypherment and could not be exchanged with the other three wheels. The British were once again locked out of naval traffic, not regaining access until NINE MONTHS later.

Some versions of enigma, like the Enigma K used by the Abwehr, were never routinely broken, in fact it was never really broken at all.

Cheers

Steve

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Very nicely summarised steve, and I stand corrected on the number of rotors. Naval enigma of course had more cypher wheels. I didn't realise it was eight wheels, having never actually seen the machine.

anyway, great post

Enigma had produced unusually important material before the Battle of Crete because the German attack was improvised and the arguments about operational and tactical issues between the commanders took fairly long time, so detailled plans were sent by wireless from Germany to Greece probably because of tight timetable. Appr. April 18 - 22, Enigma info was sent to Crete via Cairo but on 22 April London ordered all material they had received on Crete to be burnt and Cairo-Crete connection was wounded up. But after Freyberg became the commander he was kept informed on the Ultra material but it was disguised as info supplied by an SIS agent in Athens. But even without the Enigma the local commanders had deducted the essences of the German plan. That was not very difficult after German ops in Denmark, Norway and Holland. And it was made even easier by the fact that British had got the German Air-landing manual in May 1940.

Glider said:

I'm as confident as I can be that the Germans wouldn't have been able to launch a surprise invasion. The invasion force was too slow, the UK radar would have picked them up and the ports were under close PR surveillance.
I'd certainly concede that the Enigma codes were broken less frequently in 1940 but the defences were ready. All RAF bases were reasonably well defended against parachute troops and some difficult decisions made. For example all AA guns had to be capable of firing against ground targets. It made them more vulnerable against air attack as the walls were a lot lower, but the benefit was a much stronger defence.

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Well the thread OP assumes the RAF is completely defeated. This seems to imply some sort of honourable surrender where all aircraft are destroyed no more aircraft or pilots are trained. In reality if the RAF were losing the battle they would pull back and contest less and less space. The idea that the RAF would leave itself with no fighters or bombers when LW fighters could get past London is fantasy.

The M3 machines still had three coding wheels, like the Enigma I machines used by the Luftwaffe and Heer, they basically had more options as far as which were fitted. Wheels 1-V were wired the same as the Enigma I machines, but the wiring of the extra three wheels, VI-VIII, was the problem that Bletchley Park had to solve in order to read naval messages.
The BASIC principle of all enigma machines was that the letters were scrambled by a set of rotatable wheels each with 26 contacts on either side. Each contact on one side is connected (wired) to a contact on the other side in some random fashion. If you can't figure out the wiring of the various wheels you can't even begin to break the code...then you have to start to work out the wheel settings etc., etc.

The M4 machine also had eight coding wheels available, and again I-V were identical to Enigma I. It was the addition of a fourth 'active' wheel that caused the problem. This fourth wheel, added to the left of the other three could be set (at position A) to allow the four wheel M4 to be backwards compatible with the earlier machines (in other words it didn't actually do anything).

The official name for the fourth wheel was 'Zuzatzwalze', but being thinner than the others it was also known as the 'thin wheel' or sometimes 'Griechenwalze' as it was identified by the Greek letter beta or gamma.

I have a reasonable grasp of how the machines worked, but it is almost impossible to explain. How they broke them is a miracle.

Cheers

Steve

5. The long range maritime patrol plane.Doesn't matter what this is for the invasion of Britain, a couple of dozen Ju 89s wouldn't have made any real difference. Later yes (maybe???), but in Aug-Nov of 1940?
Ju 89 in operational condition is a what if, The actual aircraft were never armed, Never fitted with fuel tanks that gave more range than the Fw 200 and used a huge, high drag wing so even with better engines performance increases would be marginal. Would need Jumo 211s or DB 601s in 1940 so would be fighting for resources with existing planes.proposed turrets were of dubious utility. One man controlled the traverse manually while a 2nd man controlled the elevation, also manually.
6. Long range fighters to protect the U-boats? in 1940?
British anti-sub aircraft were a rather pathetic lot in 1940 and the standard long range overwater fighter was the Bristol Blenheim. the 10th Beaufighter was delivered Aug 3rd and 100th on Dec 7th, most (all?) going to the British night fighter force.
What kind of JU-88 fighters (or Bf 110s) do you need to counter Blenheims?
I would also note that the Germans had a shortage of Jumo 211 F & J engines at this point and most JU-88s produced in 1940 had to use the lower powered Jumo 211 B-1s and G-1s. This impacts allowable armament and fuel loads and also restricts any theoretical 4 bombers.
7. Capture the British Army at Dunkirk. A lot more doable but still doesn't solve the cross the channel problem.

Decrypting German radio traffic - and that of its allies -- was certainly a powerful tool in defeating them during WW2, but it was not the only one: just using the radio gave the British useful information. A classic example is the breaking of radio silence by the Bismarck, which was a -- perhaps the -- major factor in its location.

I'm also rather tired of people asking what Germany could have done to win, but what the British or French could do to keep Germany from winning at all.