Despite the setbacks, the Partisans remained a credible fighting force, with their organization gaining recognition from the Western Allies at the Tehran Conference#Results| and laying the foundations for the post-war Yugoslav state.
With support in logistics and air power from the Western Allies, and Soviet ground troops in the Belgrade Offensive, the Partisans eventually gained control of the entire country and of the border regions of Trieste#World War II and aftermath and Carinthia. The number of war victims is still in dispute, but is generally agreed to have been at least one million.
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.
The Wehrmacht carried out mass executions of civilians in retaliation for resistance activity e.g., the Kragujevac massacre.
Hungarian occupation troops massacred civilians (mostly Serbs and Jews) during the a major raid in southern Bačka, under the pretext of suppressing resistance activities.]]
Hungary dispatched the Hungarian Third Army to occupy Vojvodina in northern Serbia, and later forcibly annexed sections of Baranja, Bačka, Međimurje, and Prekmurje.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.