Smallest 20th century colony

The smallest colony in the world in the 20th century was the coastal fort of Sao Joao Batista de Ajuda, which was surrounded on three sides by the West African republic of Dahomey (now Benin). The fort was a Portuguese colonial possession from the early 18th century until it was forcibly incorporated into dahomey in 1961. The tiny possession had no permanent resident population but five or six Portuguese military personnel. The area of the territory was 2 ha (5 acres).