a treaty concerning the coordination of their economic policies in 1939, but the King could not persuade Adolf Hitler to guarantee Romania's frontiers. Romania was forced to cede Bessarabia and Northern Bukovina to the Soviet Union on 26 June 1940, Northern Transylvania to Hungary on 30 August, and Southern Dobruja to Bulgaria in September. After the territorial losses, the King was forced to abdicate in favour of his minor son, Michael I, on 6 September, and Romania was transformed into a national-legionary state under the leadership of General Ion Antonescu. Antonescu signed the Tripartite Pact of Germany, Italy and Japan on 23 November. The Iron Guard staged a coup against Antonescu, but he crushed the riot with German support and introduced a military dictatorship in early 1941. Romania entered World War II soon after the German invasion of the Soviet Union in June 1941. The country regained Bessarabia and Northern Bukovina, and the Germans placed Transnistria (the territory between the rivers Dniester and Dnieper) under Romanian administration. Romanian and German troops massacred at least 160,000 local Jews in these territories; more than 105,000 Jews and about 11,000 Gypsies died during their deportation from Bessarabia to Transnistria. Most of the Jewish population of Moldavia, Wallachia, Banat and Southern Transylvania survived, but their fundamental rights were limited. After the German occupation of Hungary in March 1944, about 132,000 Jews – mainly Hungarian-speaking – were deported to extermination camps from Northern Transylvania with the Hungarian authorities' support. After the Soviet victory in the Battle of Stalingrad in 1943, Iuliu Maniu, a leader of the opposition to Antonescu, entered into secret negotiations with British diplomats who made it clear that Romania had to seek reconciliation with the Soviet Union. To facilitate the coordination of their activities against Antonescu's regime, the National Liberal and National Peasants' parties established the National Democratic Bloc, which also included the Social Democratic and Communist parties. After a successful Soviet offensive, the young King Michael I ordered Antonescu's arrest and appointed politicians from the National Democratic Bloc to form a new government on 23 August 1944. Romania switched sides during the war, and nearly 250,000 Romanian troops joined the Red Army's military campaign against Hungary and Germany, but Joseph Stalin regarded the country as an occupied territory within the Soviet sphere of influence. Stalin's deputy instructed the King to make the Communists' candidate, Petru Groza, the prime minister in March