In the aftermath of the Russo-Turkish War (1877–1878) and the Congress of Berlin, Cyprus was leased to the British Empire which de facto took over its administration in 1878 (though, in terms of sovereignty, Cyprus remained a ''de jure'' Ottoman territory until 5 November 1914, together with Egypt and Sudan) in exchange for guarantees that Britain would use the island as a base to protect the Ottoman Empire against possible Russian aggression.