On: Mapping 20k ships that sank during WW II

[diegof79]

Colossus the computer created to crack Enigma was released in 1943, that’s probably the cause:

https://en.m.wikipedia.org/wiki/Colossus_computer

[diegof79 → diegof79]

Slight correction: according to Wikipedia, Colossus was based on the machine used to crack Enigma: https://en.m.wikipedia.org/wiki/Bombe

However, the timeframe matched, so around 1943, the Allies could decipher messages that allowed them to anticipate German naval movements.

[3eb7988a1663 → diegof79]

I thought the German subs used more sophisticated encryption and were more disciplined in operational procedure such that the subs were largely not decrypted by the Allies.

[dredmorbius → diegof79]

More a factor against Germany AFAIU. Japan relied on code books, not crytographic mechanisms.

Japanese Empirical codes were cracked dating to the beginning of the war AFAIU, or at the very least 1942.