Dauntless wrote: making your statement that all SDs had the same amount of armour massively false.
I never made that statement, I said that an SD is an SD, not that they had the exact same armor, though ANY SD has far better protection than ANY non-SD/DN. (plus there's the shear pucker-factor... Don't underestimate the Pucker-factor.)
During Operation Drumbeat Korvettenkapitän Reinhard Hardegen ( https://en.wikipedia.org/wiki/Reinhard_Hardegen
) commanded U-123. He stated that while approaching the US East coast he received a coded message authorizing him to break security and attack a crippled freighter off the coast of Canada which High-Command had intercepted a distress call from, requesting a tug. As he approached the area, he ran into a dense fog. He spotted 2 sets of lights in the fog, which he assumed were the freighter and tug, so he approached silently. As he got nearer and could see clearer, through the fog, he saw 2 other sets of lights in the distance ... and the 2 he was approaching ... 2 British Destroyers !!! siting dead-ahead, dead in the water. his reaction "FULL REVERSE GET US OUT OF HERE!!!
) After he extracted himself he realized he had a perfect torpedo shot on the nearest destroyer and could have blown it in half, too late. He never really got over the missed opportunity.