The French settled the largest island of the Indian Ocean (and the fourth-largest globally), Madagascar, along with a group of smaller islands nearby, namely Réunion and the Comoros. Madagascar became part of the French colonial empire following two military campaigns against the Kingdom of Madagascar, which it initiated after persuading Britain to relinquish its interests in the island in exchange for control of Zanzibar off the coast of Tanganyika, an important island hub of the spices trade. The British also held a number of island colonies in the region, including the extended archipelago of Seychelles and the rich farming island of Mauritius, previously under the French sovereignty.