[B1FF_PSUVM]

Bit unfair, dumping on people who had seventy or eighty years less experience, and profit from widely published literature and history on the topic.

I mean, it's not like they could even go read the Wikipedia piece on the German tank serial numbers info leak. Might have been a feature of a certain seminal strategy game - "you have defeated A[213 of 330]" ;-)

[WalterBright]

They did have extensive experience with spying in general, and compartmentalization of it. The compartmentalization was not applied to encryption. They also knew that losing an enigma machine to the enemy could compromise it (and did), but they just apparently assumed that no U-boot lost its enigma machine to the enemy.