Convoy survival mattered more than U-boat totals

What share of U-boat losses was credited to the Black Swan class, and does that measure its value?

Roughly twenty-eight direct credits were a small share of total U-boat losses; convoy passage and submarine suppression provide additional measures.

Roughly twenty-eight direct credits look modest beside the much larger total of wartime U-boat losses. Protecting merchant ships was the immediate purpose of convoy defence, and keeping a submarine submerged could help achieve that purpose without sinking it. Hunter-killer groups added the ability to pursue contacts while ordinary escorts protected the convoy. Coastal Command aircraft could catch boats on the surface, including boats already damaged by depth charges and unable to dive quickly. In such cases, the final attack did not capture the whole sequence of contributions. The distinction matters when comparing individual ships or services through kill totals.