Why U-boat supply ships mattered so much

Germany could send submarines to distant waters, including the Indian Ocean, but their reach remained constrained by spare parts, personnel, and consumables. Tanks without trucks and other enablers become expensive pillboxes, and warships face the same logistical limit. Converted U-boat supply vessels known as milk cows kept wolfpacks operating farther from base. Destroying one could sharply reduce an entire group's time at sea, which explains why Britain sometimes accepted intelligence risks to target them. The example makes logistics an operational centre of gravity rather than a background administrative concern.