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 1945. The Romanian administration in Northern Transylvania was soon restored, and Groza's government carried out an agrarian reform. In February 1947, the Paris Peace Treaties confirmed the return of Northern Transylvania to Romania, but they also legalised the presence of units of the Red Army in the country.