Convoy victory depended on escorts, cargo handling, and port throughput

The early US experience in 1942 shows the cost of too few escorts: destroyers had been scrapped, transferred, or assigned to higher priorities while submarines devastated coastal traffic. British and Commonwealth Flower-class corvettes and River-class frigates also filled US East Coast and Caribbean gaps. These transfers illustrate the assistance the United States received alongside its own Lend-Lease contributions. Allied production eventually supported an interlocking global convoy system, narrowing the U-boats' choice of targets. Liberty ship cargo gear constrained the weight that could be unloaded, while loading delays, convoy schedules, and congested ports limited annual crossings.