After a U-boat had completed its six month working-up period with one of the Baltic training flotillas, it was declared “Frontreif’-ready for action, and was allowed the honour of painting an insignia on the boat’s tower. Nearly all boats carried some emblem, though only half were “personal” insignia, many carrying just the flotilla’s emblem. The emblem of 7 U-Flottille, the “Bull of Scapa Flow”, Gunther Prien’s personal insignia that was taken over by his old flotilla after his death. "Laughing Sawfish" of the 9. U-Flottille, in this case carried with the city crest of Danzig on U-407.
