Germany did not keep roughly 100 U-boats at sea until late 1942, three years into the war. Strength then rose toward 160 in 1943, but the larger deployment no longer translated into more merchant tonnage sunk. U-boat losses climbed while both the number of boats at sea and the tonnage destroyed began to fall. The graph separates local submarine effectiveness from strategic success: experienced crews and heavier investment could produce a peak without forcing victory. That reversal sets up the comparison between German specialization and the expanding Allied defense.
Notable Point · 3:37-6:48
U-boat peak and tonnage curve
The force and tonnage curves show U-boat strength peaking as submarine losses rose and merchant sinkings began to fall.