The Battle of Romania comprised several operations in or around Romania in 1944, and in which the Soviet army defeated German and Romanian forces in the area, Romania changed sides, and Soviet and Romanian forces drove the Germans back into Hungary (autumn 1944).
In the 'Iassi–Kishinev Offensive', the Soviets attacked into Romania from the north-east, through the territory of present-day Moldova. Named after the area’s two major cities Iași (Iassi) and Chișinău (Kishinev), a series of military engagements took place between 8 April and 6 June with the objective of cutting the vital Axis defensive lines in the northern part of Romania, facilitating a subsequent advance by the Soviet forces into the entire Balkan region. The Soviet forces failed to overcome the German defences in the region and the offensive ultimately failed as a result primarily of the poor combat performance of Soviet troops and the effectiveness of German defensive preparations.
The second major attack of the overall offensive, between 20 August and 29 August, was the 'Iassi-Kishinev Strategic Offensive Operation' and was a crushing Soviet victory: the German [e[6th Army was encircled by the initial Soviet onslaught and was destroyed for the second time.
On 23 August, King Michael I of Romania led a coup d'état against Mareșal al Romania Ion Antonescu, the Conducător of Romania: the new government surrendered to the Allies and declared war on Germany.
The Axis front collapsed. In the north, the German 8th Army retreated to Hungary with heavy losses. Elsewhere, many Germans were cut off and taken prisoner, such as the large security and anti-aircraft force holding the Ploiești oil fields. Other fragmentary German forces fled toward Hungary as best they could, fighting the Romanian and Soviet forces, which stormed through the Carpathian mountains.
The Soviet victory in Romania caused Bulgaria to withdraw from the Axis on 26 August, and allowed Soviet forces to enter the country on 8 September.
By 24 September, nearly all of Romania was under Allied control.