An armed rebellion beginning in 1956 by the African Party for the Independence of Guinea and Cape Verde (PAIGC) under the leadership of Amílcar Cabral gradually consolidated its hold on then Portuguese Guinea. Unlike guerrilla movements in other Portuguese colonies, the PAIGC rapidly extended its military control over large portions of the territory, aided by the jungle-like terrain, its easily reached borderlines with neighbouring allies, and large quantities of arms from Cuba, China, the Soviet Union, and left-leaning African countries. Cuba also agreed to supply artillery experts, doctors, and technicians. The PAIGC even managed to acquire a significant anti-aircraft capability in order to defend itself against aerial attack. By 1973, the PAIGC was in control of many parts of Guinea, although the movement suffered a setback in January 1973 when Cabral was assassinated.