Despite the declaration of war against Great Britain and the United States, Bulgaria refused throughout World War II to declare war on the Soviet Union. The Russians, unlike the British and Americans, were popular with the Bulgarian people. They were still remembered for their assistance to the Bulgarians in the past and were viewed by the people as their liberators from Turkish rule. Not only did Bulgaria refuse to declare war on its former liberator, but it also refused to make its army available to Adolf Hitler for his eastern campaign. When Germany declared war on Russia, Bulgaria continued to retain neutrality toward, and to maintain diplomatic relations with, the Soviet Union. In the early stages of the war, before Bulgaria had declared war on the Allies, it had already begun to regain some of the land lost during the Balkan wars and World War I. Southern Dobrudzha, which had been ceded to Romania in 1913, reverted to Bulgaria by August 1940. In the spring of 1941, supporting Germany against Yugoslavia and Greece, Bulgaria regained Macedonia and part of Greek Thrace. When Bulgaria was rewarded with these lands by the Nazis, Bulgarians perceived their gains as a "historical national unification." By 1941 Yugoslavia was overrun, and some of its territories were taken by Italy, Hungary, and Bulgaria. Italy received Montenegro, Hungary took part of northern Yugoslavia, and Bulgaria gained, in addition to the much-prized Macedonia, the frontiers of southeastern Serbia. The Bulgarians at this point were once again approaching the frontiers that had been established by the Treaty of San Stefano. Internally, the country was in relatively good condition during the early stages of the war. The economy, based primarily on active trade with the Germans, was booming. The Bulgarian people perceived the fighting as essentially a "paper war" and were generally apathetic regarding their role in the war. There was little suffering within Bulgarian boundaries and little expression of hatred toward Bulgaria's ostensible enemies. Despite Bulgaria's alliance with the Nazis and Fascists, within the country Jews were for the most part protected rather than persecuted. By 1943, however, the war began to change for the Bulgarians. Slowly the Allies began to turn back German power. At this time Bulgaria was hit frequently by British and United States air raids. Because of Bulgaria's strategic significance and its declaration of war, albeit symbolic, against Great Britain and the United States, Sofia and other major Bulgarian cities became targets for American and British bombers. Sofia was reduced to little more than rubble at one point, and over 30,000 casualties were suffered by the Bulgarians.