Maybe called Bismarks because the british navy "creamed" the Bismark?

More likely that the Bismarck was by repute unsinkable I suspect.

Interesting this - Brits never say "creamed" although there is an apparent possible Cockney rhyming slang derivation in
"cream crackered" = "knackered"

I'm assuming that Cockney rhyming slang has been covered, or at least that people know you adopt the word that doesn't rhyme as the alternative word:

"I'm just going up the apples" [..and pears = stairs]
"Best put on your whistle" [..and flute = suit]