The Jassy-Kishinev Offensive was a major offensive by the Soviet Red Army's 2nd Ukrainian Front and 3rd Ukrainian Front that was carried out in eastern and southern Romania in August 1944. 1,314,200 Soviet troops, 16,000 guns, 1,870 tanks, and 2,200 aircraft took part in the assault, while they faced Army Group South Ukraine, a German and Romanian army group consisting of two German armies and two Romanian armies. The Axis forces were short of experience, armor, air support, and motor transportation, and the Soviet offensive on the German and Romanian troops near Iasi (Jassy) and Chisinau (Kishinev) would smash the Axis army group. On 21 August 1944, the German Sixth Army was cut off and found itself trapped in a cauldron between the Dniester and Pruth Rivers; its Romanian allies had surrendered to the Red Army without a fight.
The Soviet offensive's success and the collapse of the Romanian armies led to King Michael I of Romania having the fascist dictator Ion Antonescu arrested on 23 August 1944, and he appealed to his troops to surrender. On 25 August 1944, an enraged Adolf Hitler had 150 Luftwaffe aircraft bomb Bucharest in response to Romania's betrayal of the axis Powers. Romania declared war on Nazi Germany after forming an alliance with the Soviets, and the Soviet Air Force bombed the German Sixth Army as it vainly tried to fight its way westward. 200,000 German troops were lost in nine days, and the offensive came to a close on 29 August. The offensive's success allowed for Soviet troops to seize the crude oil fields of Ploesti on 30 August and then Bucharest on 31 August, and the rest of Romaia was quickly occupied. The Tsardom of Bulgaria also surrendered without a fight, as Bulgaria was never officially at war with the USSR; on 8 September, Bulgaria declared war on Germany.