World War I refits added 75 mm anti-aircraft guns, 45 mm guns on some ships, machine guns at the bow and stern, and Guiraud depth charges to ships with little spare weight. The extra equipment could reduce their speed to about 26 knots. Boutefeu was lost off Brindisi, near the Strait of Otranto, to a mine laid by UC-25, while Fourche was torpedoed by U-15. Minelaying suited early submarines because a boat could leave the area after laying a field, whereas a torpedo attack required it to remain nearby, track a faster surface target, and reach the right firing position.
Notable Point · 38:29-40:11
Wartime weapons upset a finely balanced design
World War I additions of anti-aircraft guns, machine guns, and depth charges cut speed, while losses to UC-25 and U-15 illustrate submarine mine and torpedo tactics.