In March 1941, an anti-German coup in the Kingdom of Yugoslavia prompted Hitler to order an invasion using allied Italian, Hungarian, Bulgarian and Romanian forces. Operation Marita was an invasion of Yugoslavia and simultaneously Greece. At the same time, the constituent region of Croatia broke away from Yugoslavia and joined the Axis powers. Royal Yugoslav armed forces, despite advancing against the Italians in Albania were forced to surrender after 11 days'' fighting and some 1,000 soldiers, airmen and sailors escaped to British-occupied Egypt to form Free Yugoslav units. From there, guerrilla resistance to the Axis occupiers broke out and continued with increasing strength until the end of the war under Mihailovic-s royalist ''Chetniks'' and Tito''s Communist ''Partisans'' (both supported by Britain). However, hostilities between the two movements eventually led to the Chetniks entering into local agreements with Italian occupation forces and Britain switching its support en
