Yeah I agree that there are some things that are tech related rather than production. ASW as you say, also things like radar and computers.
I like the mutually exclusive doctrine trees for fleets - convoy raiding, offensive power, defense/all rounder. The fact that some abilities show up in all of the trees (and in different positions) but some are exclusive is a nice touch. Just from the current videos posted it appears everybody goes for computers and decryption skills so far, I can't decide if that's realistic or a flaw in the tech trees (Bletchley park was British dammit
)
The fact that Stealth is a variant on subs is a good sign. I assume ASW will be a variant for DDs. That way Britain can have it's dedicated sub hunters and Japan can have it's torpedo raiders.
No system is going to be perfect but I do like the HOI4 focus being on what forces can you get into the field.
Every country had good decryption and it's just that the Allies were way better at using Ultra than the Axis were on their decrypts.
The same book on the Japanese merchant marine points out that the Japanese broke several of the British and American codes and almost all of the Chinese ones. They just were worse about using it. Every major combatant in WW2 remained surprisingly confident about their own codes even as they cracked and read their opponents.
But even decryption and intelligence stuff goes beyond tech. You have to teach the codes. You have to practice with them. You have to make sure your merchant ships aren't broadcasting their positions at noon.
ASW is the best case... The Allies did develop a lot of tech, hydrophones, sonar, special airplane radar, depth charge launchers, depth charge timers and detonators, destroyer escorts, escort carriers... etc.
But more important than all that was that they had a dedicated command structure for handling convoys and they put a ton of effort into production, tactics and research to fight subs. The tech tree as it stands now only makes sub defense an issue of production.
From the end of the book about Japan's merchant marine, talking about Japan's lack of preparation.
The entire antisubmarine effort endured additional harm from the Navy's personnel policies and doctrinal conceptions, which mirrored and reinforced the resource allocations of the armaments program. Maritime protection was "defensive" and hence unimportant, so it did not attract the most promising officer candidates or the attention of bright minds. One can only imagine what strides Japanese antisubmarine weaponry and tactics might have made in the interwar period with the application of the energy and ingenuity that was devoted to the "decisive battle." The same engineers who developed superb torpedoes and worked feverishly to pack an extra salvo of them into the design of fleet destroyers might well have devised a a more effective depth charge, while the staff officers who spent years developing midget sub tactics could easily have planned efficient convoy sailing formations and submarine search patterns.
Other navies committed similar errors in their assessment of the underwater threat; the British, with far greater historical reason to be wary of the submarine, never conducted any convoy protection exercises in the interwar period, and in early 1942 the US Navy stubbornly ignored the necessity of convoys even as U-boats were littering the floor of the Western Atlantic with the broken hulls of US merchantmen. However, the Allies reacted more quickly and forcefully to the submarine menace than the Japanese. They initiated crash programs for construction of escort vessels, sponsored technical and tactical research into all aspects of the problem, accepted the convoy principle and developed it into a highly flexible and effective instrument, and established antisubmarine warfare training schools on a grand scale.
I don't think that commerce protection should be exclusive. I just think that say Germany could get away with not researching it since they have no convoys to defend.
But it needs to be in addition to whatever doctrine tree the Navy is on. The British and the Americans used different naval doctrines but the way they did ASW was the same.
I'll accept the variants as a good compromise, but I still miss destroyer escorts.
