HMS Spearfish and the strategic cost of damage

HMS Spearfish caught Lützow on 11 April 1940 after the cruiser left her torpedo-boat escort behind and relied on 24-knot speed to avoid submarines. Spearfish was positioned across her route and put a torpedo into her stern, leaving the cruiser unable to steer and dependent on a tow. Repairs, subsequent damage, and difficulties returning to service kept Lützow out of effective service until May 1942. During that period she consumed dockyard capacity, materials, funding, and attention, while also becoming a target for British air attack. The threshold for repairing or writing off a hull changes with the stage of a war and the number of replacements available. An overstretched fleet may have to repair damage that a larger force late in a conflict can afford to write off. Immobilizing Lützow therefore imposed a continuing cost on Germany's small navy.