Hungary–Romania relations
During World War II, Hungary and Romania became allies and participated in the war against the Soviet Union. But after the coup on 23 August 1944 Romania switched sides and fought against Hungary. Consequently, Soviet and Romanian troops invaded Hungary, occupied Northern Transylvania by October 1944 and re-established the Romanian administration in the region in March 1945. The 1947 Treaty of Paris reaffirmed the borders between Romania and Hungary as originally defined in Treaty of Trianon 27 years earlier, thus confirming the return of Northern Transylvania to Romania.
Michael I of Romania
Although the country's alliance with the Nazis was ended, the "coup" sped the Red Army's advance into Romania. The armistice was signed three weeks later on 12 September 1944, on terms the Soviets virtually dictated. Under the terms of the armistice, Romania recognized its defeat by the USSR and was placed under occupation of the Allied forces, with the Soviets, as their representative, in control of media, communication, post, and civil administration behind the front. The coup effectively amounted to a "capitulation", an "unconditional" "surrender". It has been suggested that the "coup" may have shortened World War II by six months, thus saving hundreds of thousands of lives.