With Soviet troops crossing the border and the Axis collapsing across the Balkans, the Fatherland Front—a coalition dominated by communists—overthrew the pro-Axis government of Bulgaria on the night of September 8-9. The new government promptly declared war on Germany, completing Bulgaria's dizzying wartime reversal from Axis satellite to Soviet ally.
Bulgaria's monarchy had spent the war in an uneasy balancing act: declaring war on Britain and the United States while refusing to fight the Soviet Union, with whom it shared deep cultural and religious ties. That balancing act collapsed in the late summer of 1944 as the Red Army swept through Romania and reached Bulgaria's northeastern frontier.
On the night of September 8 into September 9, Fatherland Front partisans and sympathetic army units seized government buildings, radio stations, and the war ministry in Sofia with minimal bloodshed. Kimon Georgiev became prime minister of a coalition government that included communists, agrarians, and Zveno officers, though communists quickly came to dominate real power.
Within days the new government declared war on its former Axis partner Germany, and Bulgarian forces began fighting alongside the Red Army in Yugoslavia and Hungary. The coup set the stage for four decades of communist rule, cementing Bulgaria's postwar fate as one of the Soviet bloc's most loyal members—so loyal that Todor Zhivkov's regime would later be nicknamed 'the sixteenth Soviet republic.'