He ranked No. 24 on the list of Germany’s Second World War U-boat aces but, in sheer chutzpah, few could compare with Reinhard Hardegen.

Hardegen died in Germany on June 9 at age 105, the last of a breed both reviled and respected for preying on all manner of Allied ships from beneath the waves—a cloak of invisibility that offered them large measures of both risk and reward...