territorial revision to be decided along ethnic lines. In March 1939, the Czecho-Slovak Republic was dissolved, Germany invaded it, and the Protectorate of Bohemia and Moravia was established. On 14 March, Slovakia declared itself to be an independent state. On 15 March, Carpatho-Ukraine declared itself to be an independent state. Hungary rejected the independence of Carpatho-Ukraine and, between 14 March and 18 March, Hungarian armed forces occupied the rest of Carpathian Ruthenia and ousted the government of Avgustyn Voloshyn. By contrast, Hungary recognized the Nazi puppet state of Slovakia led by the Clerical Fascist Jozef Tiso. In September 1940, with troops massing on both sides of the Hungarian-Romanian border, war was averted by the Second Vienna Award. This award transferred the northern half of Transylvania to Hungary, with a total area of 43,492 km2 and a total population of 2,578,100 with a 53.5% Hungarian majority according to the 1941 census. By dividing Transylvania between Romania and Hungary, Hitler was able to ease tensions in Hungary. In October 1940, the Germans initiated a reciprocity policy between Romania and Hungary which was continued until the end of World War II. The region of Sub-Carpathia was given special autonomous status with the intention that (eventually) it would be self-governed by the Ruthenian minority. During World War II 1941–1945 After being granted part of southern Czechoslovakia and Subcarpathia by the Germans and Italians in the First Vienna Award of 1938, and then northern Transylvania in the Second Vienna Award of 1940, Hungary participated in their first military maneuvers on the side of the Axis powers in 1941. Thus, the Hungarian army was part of the invasion of Yugoslavia, gaining some more territory and joining the Axis powers in the process. On 22 June 1941, Germany invaded the Soviet Union in Operation Barbarossa. Hungary joined the German effort and declared war on the Soviet Union on 26 June, and entered World War II on the side of the Axis. In late 1941, the Hungarian troops on the Eastern Front experienced success at the Battle of Uman. By 1943, after the Hungarian Second Army suffered extremely heavy losses at the river Don, the Hungarian government sought to negotiate a surrender with the Allies. On 19 March 1944, as a result of this duplicity, German troops occupied Hungary in what was known as Operation Margarethe. By then it was clear that Hungarian politics would be suppressed according