Portrayed in the southern lock at the French port of Saint Nazaire during the Autumn of 1941 are from left: U552, commanded by Kapitanleutnant Erich Topp, U567, commanded by Oberleutnant zur See Engelbert Endrass and U93, commanded by Oberleutnant zur See Horst Elfe. Saint Nazaire was home for two U-boat flotillas: 7. U-Flotille, the Wegener Flotilla and 6.U-Flotille, the Hundius Flotilla. It produced some of the top U-boat commanders including Topp, Endrass, Prien and Kretschmer. The base reached a peak of activity in mid 1943, however, by the end of the war the entire port had been flattened by the allied air forces. The only buildings to survive the onslaught were the bomb proof U-bunkers which can still be seen to this day.