A raider did not need to stop all shipping by itself to affect the war. Disruption lasting days or weeks already imposed costs, while enough diverted escorts could expose major routes carrying trade and troops. Submarines could then exploit the weakened protection, making both arms part of the same operational plan. German admirals appear to have understood this interaction better than Hitler. His growing hostility to major surface ships may have reflected both their losses and the scale of Royal Navy operations mounted against them.
Notable Point · 4:10-5:09
Surface raiders could draw escorts from critical routes
German surface raiders could divert escorts from Britain's most important supply routes and give submarines openings against the weakened defenses.