The protectorate of Northern Nigeria was proclaimed at Ida by Frederick Lugard on January 1, 1897. The basis of the protectorate was the 1885 Treaty of Berlin which broadly granted Northern Nigeria to the British sphere of influence, on the basis of their existing protectorates in Southern Nigeria. Hostilities with the powerful Sokoto Caliphate soon followed. the Emirates of Kotogora and Ilorin were the first to be conquered by the British. In February 1903, the great fort of Kano, seat of the Kano Emirate was captured, Sokoto and much of the rest of its Caliphate soon capitulated.