The Settlement maintained its own fire-service, police force (the Shanghai Municipal Police), and even possessed its own military reserve in the Shanghai Volunteer Corps (). Following some disturbances at the British concession in Hankow in 1927, the defences at Shanghai were augmented by a permanent battalion of the British Army, which was referred to as the Shanghai Defence Force (SDF or SHAF), and a contingent of US Marines. Other armed forces would arrive in Shanghai; the French Concession had a defensive force of Troupes de marine and Annamite suppletive troops from French Indochina, the Italians also introduced their own marines, as did the Japanese (whose troops eventually outnumbered the other countries' many times over).