Mostlyharmless, the subject has been done to death already.
Good advice!! However, once you start rolling downhill, it is hard to stop! Also, I am no good at writing timelines especially when I do not know how they will end. However, I can always look at your expert judgements and follow the consensus.
The initial POD is that Hitler is crazy. “In Hitler's mind the threat of world war, the Americans and the Jews were inextricably intertwined” - Tooze “The Wages of Destruction”, Page 424. Confronted with war with Britain and France in September 1939, Hitler decides that he must defeat France first but that if he succeeds, America will enter the war rather than accept a German victory. He decides that the only hope is to follow up victory in France with an invasion of Britain before the British can raise and equip an army capable of offering significant resistance. He establishes a group headed by Jodl and including officers from the Luftwaffe, led by Hans Geisler, and Kriegsmarine, led by Wilhelm Marschall, as well as Speer as his personal representative on economic planning and asks Jodl to send a brief report to him on progress everyday. He also persuades Goering to accept that it will be necessary to sacrifice longer term development of war industries in favour of strengthening the Luftwaffe for operations in 1940, with the carrot that the LW can establish a Luftflotten sized anti-shipping force and prove that air power can dominate the sea.
Within a few weeks, the reports reach agreement on priorities: anti-shipping aircraft with fighters to escort them (I suspect that the LW might go wrong on this point by producing more Bf-110s rather than Bf-109s with drop tanks but that would depend on the particular LW officers involved), large surface warships and landing craft. S-boats and R-boats should also be built in large numbers but their limitations were recognised. Submarines were also to be completed as quickly as possible if they could be ready for use in 1940. Large numbers of transport gliders were also to be constructed and a large glider was also ordered that could transport light tanks or artillery. A bright officer pointed out that this would also need a specialist towing aircraft, so Heinkel promised to design a variant of the He-111 which could be produced quickly and Messerschmidt offered to add six Bramo-323 engines to the glider to produce a large transport.
Finding pilots for the additional aircraft proved to be more difficult than producing the aircraft. There were two issues: trainers and instructors. Paul Deichmann suggested that obsolete Ju-86 bombers could be rapidly assembled from existing parts to help train bomber pilots and this was agreed (OTL rejected). The provision of basic trainers was and remained a problem. Some were purchased from Italy at what many called a ridiculously high price, especially as the controls needed to be altered to German standards, and there was some increase in production at home. Instructors were made available by releasing many pilots from front line units once Hitler could be persuaded that weather and ammunition shortages made an early attack on France impossible but of course the same weather interfered with training.
The anti-shipping force was set up under Erhard Milch as Luftflotte 5 with Hans Geisler as his deputy. Fortunately, a good relationship existed between Admiral Marschall and Geisler, himself originally a naval officer, and this enabled an Air-Naval Liaison Office to ensure rapid communication between the services. In particular, aerial reconnaissance reports were read on arrival by naval officers and naval movements were passed to Luftwaffe units (preventing
http://en.wikipedia.org/wiki/Operation_Wikinger). The last was the subject of some argument until Milch agreed to humour what was regarded as naval paranoia by adopting the KM's bigram system for sending the indicators of Enigma signals. Perhaps Milch was also happy that his signals were now secure from the rest of the Luftwaffe, although that advantage was lost on 1st July when the Luftwaffe generally adopted the new system.
Major Martin Harlinghausan, who had already developed the Swedish Turnip method of attacking ships, was a strong advocate of the development of torpedo bombers. However, it was soon clear that the German torpedoes developed by the KM for use by aircraft were essentially useless and Goering gave permission for the Luftwaffe to design their own. Both the Italian and the Japanese Naval Attachés admitted that their navies had designed better torpedoes but the question was, how to persuade them to release their designs to Germany. Jodl approached Hitler and received his permission to trade any necessary weapon or industrial secrets and the result was that radars such as the Wurzburg and the design of tools needed to build fuel injectors for aero-engines were soon given to both nations. The Italians agreed in addition to carry the equipment to and from Japan on a cruiser, which was official showing the flag in support of the Italian forces in China. In fact, Japanese blueprints were also sent in multiple parts chained to diplomats wrists via the USSR. Even after examining two reasonable designs, it was hard to design and produce a satisfactory torpedo and too few were available to play any role in the Norwegian invasion. As he had for the previous two month, Martin Harlinghausan spent most of April watching his pilots practise torpedo bombing. All the torpedoes were recovered and those that had not run true were examined and orders were sent to strengthen parts that failed, which did nothing to speed up production. Oddly the biggest single improvement arose quite accidentally when the cine film that had been taken to improve the training was reviewed. It was noticed that the angle of entry to the water correlated well with whether the torpedo ran true, so a wooden tail shroud was added to try to ensure a good, nose first, entry angle and prevent roll. Eventually the combination of strengthened structure and the wooden additions produced a torpedo that could be dropped from 1,500 metres at 350 knots at the expense of additional weight and drag. Meanwhile rigorous tests of Italian, Japanese and German model fuses showed the superiority of the new Italian models especially to any of the German designs. This information was passed to the KM by several routes and after some reluctance began to be accepted. The Luftwaffe's torpedoes had entered production early in 1940 but remained mired in modification until the end of May. Only in June 1940 did torpedoes arrive that were immediately fit for use although older torpedoes were frantically modified and around 400 torpedoes were available on July 1st 1940 with a further 100 arriving during the next week of which more than half came from modification workshops.
One difficult choice for Major Harlinghausan was whether to recommend the He-111 or the Ju-88 as the main torpedo carrier. The He-111 was easier to control near the water but the Ju-88 had better performance after it had dropped its torpedoes and could also use its dive brakes to allow a faster initial approach. To make things more complicated, Milch himself had become involved by criticising the Ju-88's flying characteristics, so that there was some temptation to wait for the extend wings of the A5 variant. Fortunately, the improvement in the strength of the torpedoes eased the problems. Neither dive brakes nor flying very near the water were now necessary, so both aircraft became satisfactory carriers. Finally, to skip ahead and apparently to mock the idea that production had been rationalized, 12 Fieseler Fi-167s arrived as the Battle of France was ending to equip the carrier Graf Zeppelin, whose construction had been suspended the previous September! Major Harlinghausan realised that these aircraft did have unique advantages and formed them into a night attack Stafel to use their very low stalling speed.
The Norwegian campaign was launched on 9th April 1940 in response to the British Operation Wilfred. It was aimed at trying to sink as many British warships as possible and completing the training of the anti-shipping force including finding out which tactics worked best. Naturally, there was a great reluctance to risk the KM surface ships although Scharnhorst and Gneisenau were dispatched far north of the main landings at Bergen, Kristiansand and near Oslo at a site advised by Quisling (together with seizing Sola airfield using paratroops). Despite the commitment to low risk, the KM still lost two light cruisers in the first few days although the strong destroyer escorts did manage to frustrate some submarine attacks on returning ships. Apart from the units involved in training, almost all of Luftflotte 5 was committed and their 9th April attacks on both a major portion of the British fleet, including the battleships Rodney and Valiant, and on a detached force of cruisers and destroyers was their first opportunity to show the results of their training. Much the most effective attack was by 40 Ju-87R flying from the newly captured field at Aarhus against the cruisers off Bergen, which score hits on the cruisers Southampton, Glasgow and Sheffield and the destroyer Gurkha. Southampton, hit at least four times, and Gurkha sank. The two engined bombers meanwhile had hit both Rodney and Valiant, although without causing serious damage. As a result of these attacks, the British abandoned all attempts to use surface forces to prevent German forces sailing to Oslo and, by mid May, the German forces were advancing towards Trondheim and their Anglo-French-Norwegian opponents were suffering under the weight of German aerial superiority.
Of course, by mid May, the world's eyes were on France rather than Norway although it is hardly necessary for me to tell that well known story. Perhaps the most obvious point where the plans for the invasion of Britain collided with the need to win the Battle of France occurred on the morning of 24th May when Hitler, desperate to ensure that the BEF was captured in France, overrode von Rundstedt's order to Guderian to halt at the Aa river and ordered 1st Pz to take Dunkirk, leading to severe street fighting and heavy loses when the division was also bombarded by the Allied Navies. Hitler's interference was heavily criticised within OKH and it has been noted that the Luftwaffe could have probably prevented any evacuation. The fighting around Dunkirk is also notable for the first use of torpedo bombers by the Luftwaffe, although the torpedoes had not been fully modified, and the use of the very rapidly built and trained force of S-boats. Ironically, the most effective weapon against the allied shipping on that occasion proved to be the Ju-87s of Luftflotte 2 and 3 which had hardly practised attacking ships!
Luftflotte 5 was in action against the RN at the same time as the Dunkirk fighting when they attacked shipping off Central Norway, which was evacuating Anglo-French forces from the Trondheim area. Several units were initial taken to Narvik. However, with the fall of France, the British staffs were finally able to persuade Churchill that Narvik could not be held and a further evacuation followed in late June, this time with fewer casualties partly because the principle anti-shipping units of the LW were being withdrawn from Norway for action elsewhere.
It was unusual for senior officers of the Wehrmacht to indulge in philosophical reflections on the significance of their contributions but the morning of the 4th July 1940 found Colonel-General Jodl and General Geisler together eating cheese on rye bread with, a great luxury, real coffee. While either could surely have found important activities, nothing seemed more urgent than waiting for news.
“Everything left harbour last night?” began Jodl.
“So the Navy tells me” responded Geisler.
“What has the Sealion planning team really achieved over its ten months?” asked Jodl
“Well apart from making the detailed plans for Sealion, we have probably driven the construction of about an additional 800 landing craft, 200 S-boats, 800 gliders and over one thousand aircraft together with producing pilots to fly them.”
“How do you calculate a thousand aircraft?”
“There must be almost a thousand extra combat aircraft even excluding trainers and transports. Nearly 400 extra He-111s, 200 extra Ju-87s – mostly Rs, 200 extra Bf-109s and a few extra Ju-88s, Do-17s and Bf-110s.”
“And we have lost all the new factories and oil plants that we will need if this invasion does not succeed not to mention, as Doenitz does every time we see him, well over 100 submarines that could have been built over the next year!”
“And Bismarck, Tirpitz, Prinz Eugen and Seydlitz are still not quite ready despite all our efforts.”
At which moment, a young officer approached with the totally unexpected news that the British had started to take over the French fleet in Britain and that a battle squadron was threatening Mers el Kebir.