During World War II, Ukrainian became an area of of German - Polish and German - Soviet conflicts.
On August 23, 1939 Germany and Russia signed a pact, which provided for the division of Poland and the annexation of the Baltic states by the USSR. On September 1, 1939 Germany invaded Poland. German armies occupied the western and central parts of Poland and the Soviets took Ukrainian and Belorusian territories within a matter of three weeks. The boundary between German and Soviet territories was fixed at the Sian - Solokia - Buh Rivers — the Sian region (Posiannia), the Lemko region and western Pidliassia (Pidlissia) under German control while the rest went to the Soviet Union, which incorporated the territory into the Ukrainian SSR, except for the northern part of Polissia, which was joined to the Belorussian SSR. In an agreement between the USSR and Rumania on June 28, 1940, northern Bukovyna and Bessarabia were ceded to the USSR. Northern Bukovyna and the Khotyn, Akkerman and Izmail counties of Bessarabia were incorporated into the Ukrainian SSR. The remaining portion of Bessarabia was constituted as an autonomous region within the Ukrainian SSR as the Moldavian ASSR.
On June22, 1941 Germany attacked the Soviet Union and, between 1941 and 1942, German armies occupied the western part of the Soviet Union as far as the Caucasus region and the Grozny - Stalingrad - Orel line, which included the entire territory of Ukraine.
Germany annexed Galicia (Halychyna) on August I, 1941 to the General Government, under the name "District Galicia "and gave northern Bukovyna, Bessarabia and the territory between the Boh and Dnister Rivers, called "Transnistria," to Rumania, in order to secure an alliance. The German Reich placed the occupied territory of Ukraine under the control of an administrative body called "Reichcommissariat Ukraine."
After three years of successes the tide turned against the Germans. They were defeated in the battles of Stalingrad and Kursk. Soviet armies recaptured most of Ukrainian territory east of the Dnipro River in autumn of 1943, pushed on to capture the right bank in spring of 1944, broke through the German front at Brody in July and, by October, occupied all of the west Ukrainian territories. The war ended on May 8, 1945 with Germany's
unconditional surrender.
Military campaigns and occupation by Germany and the Soviet Union had a devastating effect on Ukrainian life. Ukraine was subjected to relentless exploitation of its economic resources. In addition, hundreds of thousands of people were deported to forced labor camps in Germany. These conditions provided widespread support for the resistance movement of the Ukrainian Insurgent Army (UPA — "Ukrainska Povstanska Armia") which began in 1942, conducting raids and disrupting German supply lines.