The signing of the Tripartite Pact with Germany on March 25, 1941, which was intended to prevent the involvement of the country in the war, led to a coup d'état, popular discontent and demonstrations. Prince Petar II, who was still under age, was proclaimed king, by which was the regency of Prince Pavle was abolished. The government led by General Simović was established.
The period of life and survival under occupation began with the attack on Belgrade without a declaration of war, the entry of German troops into the city and the surrender of the army. Belgrade was the capital of a reduced Serbia governed by a German military police commander and collaborationist authorities: Aćimović's commissar administration and Milan Nedić's Government of National Salvation. In the territory of the city, two concentration camps were established: Banjica and Staro Sajmište. Mass executions were usually carried out at a military firing range in Jajinci. While the war was still going on, in 1944, the city was on several occasions bombed by Anglo-American forces.
After the liberation of Belgrade by the People's Liberation Army of Yugoslavia and the Red Army on October 20, 1944, the city became the leading centre of military and political activities. In the period of rebuilding and construction, vast human and material resources were mobilized. With the abolition of the monarchy and the proclamation of the Republic, the elected city authorities replaced the former Executive Board. The urban development of the city continued during the following period. The reliance on the USSR in foreign policy was abandoned due to the Cominform Resolution in 1948, and since then the country began to open up to the West. The Conference of Non-Aligned countries paved a new direction in Yugoslavia's foreign policy. After the death of Josip Broz Tito, the system began to collapse at all levels.
In the years of the dissolution of Yugoslavia, Belgrade was coming through a dramatic period. It lived through the 1990s in a context defined by various conflicting political ideas and programmes. In the dusk of the 20th century, Belgrade was once again exposed to prolonged bombing.
In 2000, on October 5, the citizens from all over Serbia, gathered in Belgrade, hammered out the recognition of the election results and the victory of the Democratic Opposition of Serbia.