13 December, 1943, 12.20: U-172 goes under.I Zentralmaat Markgraf, acting upon orders of LI Löffler, has opened the diving tank valves, leaving II Zentralmaat Schuy to his chosen fate. Already underwater, the bow can be seen clearly as U-172 continues to make way and the crewmen who manned her battered conning tower make their escape. At least one of them can be seen outlined in the wake abaft the lower, already flooded AA platform. Note that at this stage there is not one gun or heavy machine gun splash to be observed near the boat; this observation puts into doubt Herbert Plottke's assertion that the surrounding American craft continued to fire during the.