Alger was the lead ship of her class of protected cruisers built for the French Navy in the late 1880s and early 1890s. Alger and her two sister ships were ordered during the tenure of Admiral Théophile Aube as Minister of Marine according to the theories of the Jeune École doctrine. The ships were intended as long-range commerce raiders, and they were armed with a main battery of four 164 mm (6.5 in) guns, were protected by an armor deck that was 50 to 100 mm (2 to 4 in) thick, and were capable of steaming at a top speed of 19.5 knots (36.1 km/h; 22.4 mph).