A mixed convoy strategy could outproduce and outlast a submarine-only attack even when both sides began with similar maritime capacity. Germany built nearly 700 Type VII boats, but combat losses, damaged boats, and the need for milk-cow supply submarines kept the usable force much smaller. Damaged escorts could often be towed home, while a damaged U-boat and its experienced crew were far harder to recover. The Royal Navy built 225 original and 69 modified Flower-class corvettes, losing 33 during the war, including 22 to submarines. It also completed 86 Hunt-class escort destroyers and expanded the River-class frigate order from 30 to 151, of which five were lost. Trawlers, converted V and W-class destroyers, improved ASDIC, centimetric radar, Hedgehog, Squid, and heavier depth-charge batteries steadily widened the Allied advantage.
Chapter · 6:55-11:57
Escorts outbuild submarines
Production and loss figures for Type VII U-boats, Flowers, Hunts, Rivers, trawlers, and converted destroyers explain the escort advantage.