After the fall of France to Nazi Germany in May 1940, the UK was the only empire in conflict with the Axis powers, and Prince Paul and the government saw no way of saving Yugoslavia except through adopting policies of accommodation with the Axis powers.
The government tried to negotiate with the Axis on cooperation with as few concessions as possible, while attempting secret negotiations with the Allies and the Soviet Union, but those moves would fail to keep the country out of the war.
Clockwise from top left: Ante Pavelić visits Adolf Hitler at the Berghof, Stjepan Filipović hanged by the occupation forces, Draža Mihailović confers with his troops, a group of Chetniks with German soldiers in a village in Serbia, Josip Broz Tito with members of the British mission Military operations in World War II in Yugoslavia began on 6 April 1941, when the Kingdom of Yugoslavia was swiftly conquered by Axis forces and partitioned between Germany, Italy, Hungary, Bulgaria and client regimes.
Subsequently, a guerrilla liberation war was fought against the Axis occupying forces and their locally established puppet regimes, including the Independent State of Croatia and the Serbian Government of National Salvation, by the KPJ-led republican Yugoslav Partisans.
Air force officers opposed to the move staged a coup d'état and took over in the following days.
These events were viewed with great apprehension in Berlin, and as it was preparing to help its Italian ally in its war against Greece anyway, the plans were modified to include Yugoslavia as well.