It was formed to supplement the Zanzibar garrison after defeat in the 4 November 1914 Battle of Tanga left British forces in the region on the defensive.

[1] The Zanzibar Volunteer Defence Force was a development of the Town Guard that had been formed shortly after the start of the war to help the small garrison of one KAR company to defend the protectorate.

After the defeat at Tanga the British resident in Zanzibar requested a full battalion of infantry to defend the protectorate; he received four companies of the Gwalior Rifles that had survived the battle.

[3] A history of the war states that "practically every able-bodied member of the small British community" joined the Zanzibar Volunteer Defence Force.

[4] In April 1915 the KAR company was withdrawn from the garrison and they were followed by the Gwalior Rifles in October; Zanzibar was thereafter required to be self-sufficient in defence.