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.
RWD 13
After the outbreak of World War II, 28 Polish RWD-13 were evacuated to Romania (23 RWD-13 and 5 RWD-13S). After the fall of Poland, they were taken over by Romanian civil and military aviation. After Romania joined the war on the Axis side and took part in the attack on the USSR, RWD-13 were used as liaison aircraft by the Air Force. Especially famous were air ambulances, used by the "Escadrila Albă" (White Squadron), flown by women. Twenty-one survived the war and the remaining ones were used in Romania until the 1950s.