The S-class boats were intended for Mediterranean service, but Gibraltar put them far from support at the entrance to an intense anti-submarine campaign. The Allies tried to stop Axis submarines moving in either direction, while Axis forces sought to deny the same passage to Allied boats. Minefields and aggressive patrols made the strait a dangerous bottleneck. No confirmed friendly-fire sinking is identified here, though some unexplained losses may have involved Allied mines. Those hazards restricted submarine deployments and the rules governing movement around Gibraltar.
Notable Point · 10:01-12:22
Gibraltar and the S-class submarine bottleneck
S-class submarines based at Gibraltar faced a heavily defended entrance where each side tried to control movement into and out of the Mediterranean.