The Nazi invasion of Poland on Sept. 1, 1939, marked the beginning of World War II. By mid-September, in accordance with the secret protocols of the Molotov-Ribbentrop Pact, western Volhynia and most of Galicia were occupied by Soviet troops and soon officially incorporated into the Ukrainian S.S.R. In June 1940 northern Bukovina was occupied and shortly annexed to Soviet Ukraine from Romania. The replacement of Polish and Romanian by the Ukrainian language in state administration and education was offset by a suppression of all existing organizations, Sovietization of institutional life, and arrests of political leaders and community activists. By mid-1941 more than one million people had been deported to the east, including large numbers of Poles and Jews.
The ethnically mixed western borderlands, with more than 500,000 Ukrainians, were included in the administrative region of Poland established by the Nazis. A limited linguistic and cultural revival in the heavily Polonized area was permitted under German oversight, but political activities were banned, except for the OUN. The OUN itself was rent by factional strife between the followers of Andry Melnyk, who headed the organization from abroad after the assassination of Konovalets by a Soviet agent in 1938, and the younger supporters of Stepan Bandera with actual experience in the conspiratorial underground. The split became permanent after a congress held in Kraków in February 1940, when the Melnyk and Bandera factions developed into separate organizations (OUN-M and OUN-B, respectively) differing in ideology, strategy, and tactics.
The surprise German invasion of the U.S.S.R. began on June 22, 1941. During their hasty retreat the Soviets shot their political prisoners and, whenever possible, evacuated personnel, dismantled and removed industrial plants, and conducted a scorched-earth policyblowing up buildings and installations, destroying crops and food reserves, and flooding mines. Almost four million people were evacuated east of the Urals for the duration of the war. The Germans moved swiftly, however, and by the end of November virtually all of Ukraine was under their control.
Initially, the Germans were greeted as liberators by much of the Ukrainian populace. In Galicia, especially, there had long been a widespread belief that Germany, as the avowed enemy of Poland and the U.S.S.R., was the Ukrainians' natural ally for the attainment of their independence. The illusion was quickly shattered. The Germans were accompanied on their entry into Lviv on June 30 by members of OUN-B, who that same day proclaimed the restoration of Ukrainian statehood and the formation of a provisional state administration; within days, the organizers of this action were arrested and interned in concentration camps (as were both Bandera and, later, Melnyk). Far from supporting Ukrainian political aspirations, the Nazis in August attached Galicia administratively to Poland, returned Bukovina to Romania, and gave Romania control over the area between the Dniester and Southern Buh rivers as the province of Transnistria, with its capital at Odessa. The remainder was organized as the Reichskommissariat Ukraine.
In the occupied territories, the Nazis sought to implement their racial policies. In the fall of 1941 began the mass killings of Jews that continued through 1944; as many as 600,000 perished, some 70,000 executed at Baby Yar in Kiev alone. In the Reichskommissariat, ruthlessly administered by Erich Koch, Ukrainians were slated for servitude. The collective farms, whose dissolution was the fervent hope of the peasantry, were left intact, industry allowed to deteriorate, and the cities deprived of foodstuffs as all available resources were directed to support the German war effort. Some 2.5 million people were taken to Germany as slave labourers. Cultural activities were repressed, and education was limited to the elementary level. Only the revived Ukrainian Orthodox church was permitted to resume its work as a national institution. Somewhat better was the situation of Ukrainians in Galicia, where, under centralized control, restricted cultural, civic, and relief activities were permitted.
Under such conditions of brutality, Ukrainian political activity, predicated originally on cooperation with the Germans, increasingly turned to underground organizational work and resistance. The OUN groups that streamed eastward in 1941 were soon subjected by the German authorities to repressive measures, including execution; they propagated their nationalist views clandestinely and through their contact with the local population began to revise their ideology in a more democratic, pluralist direction. In eastern and central Ukraine, secret Communist Party cells maintained an underground existence, and a Soviet partisan movement developed in the northern forests. Early in 1942 began the formation of nationalist partisan units in Volhynia, and later in Galicia, that became known as the Ukrainian Insurgent Army (UPA). As well as conducting guerrilla warfare with the Germans, the Soviet partisans and the UPA fought each other.
After their victory over the Germans at Stalingrad in early 1943, the Soviets launched a counteroffensive westward. In mid-1943 the Germans began their slow retreat from Ukraine, leaving wholesale destruction in their wake. In November the Soviets reentered Kiev. With the approach of the front, guerrilla activity in Western Ukraine intensified, and bloody clashes that claimed large numbers of civilian victims occurred between Ukrainians and Poles. In spring 1944 the Red Army began to penetrate into Galicia, and by the end of October all of Ukraine was again under Soviet control.
The Soviet victory, the Red Army's occupation of eastern Europe, and Allied diplomacy resulted in a permanent redrawal of Ukraine's western frontiers. With compensation of German territories in the west, Poland agreed to the cession of Volhynia and Galicia; a mutual population exchangeand the subsequent deportation of the remaining Ukrainian population by Poland to its new western territoriescreated for the first time in centuries a clear ethnic, as well as political, Polish-Ukrainian border. Northern Bukovina was reoccupied in 1944 and recognized as part of Ukraine in the Paris Peace Treaty of 1947. Transcarpathia, which had reverted from Hungary to Czechoslovakia in 1944, was ceded to Ukraine in 1945 by a Czech-Soviet government agreement. In 1945 Ukraine became a charter member of the United Nations and subsequently became a signatory of peace treaties with Germany's wartime alliesItaly, Finland, Romania, Hungary, and Bulgaria.
Ukraine's human and material losses during World War II were enormous. Some five to seven million people perished. Even with the return of evacuees from the east and the repatriation of forced labourers from Germany, Ukraine's estimated population of 36 million in 1947 was almost five million less than before the war. Ten million were homeless, as more than 700 cities and towns and 28,000 villages were destroyed. Only 20 percent of the industrial enterprises and 15 percent of agricultural equipment and machinery remained intact, and the transportation network was severely damaged. The material losses comprised an estimated 40 percent of Ukraine's national wealth.