Although the wide majority of Ukrainians fought alongside the Red Army,[28] some elements of the Ukrainian nationalist underground fought both Nazi and Soviet forces, forming the Ukrainian Insurgent Army in 1942. While other Ukrainians initially collaborated with the Nazis, having been ignored by all other powers. In total, about 4.5 million ethnic Ukrainians fought in the ranks of the Soviet Army[28][b] and another 43,500 Ukrainians as pro-Soviet partisan guerrilla units at their peak in 1943.[29] On the other hand, due to the Ukrainian Insurgent Army's unconventional structure, estimates are much less accurate, ranging anywhere from 25,000 to 200,000 Ukrainians.[30] In 1941 the German invaders and their Axis allies initially advanced against desperate but unsuccessful efforts of the Red Army. In the encirclement battle of Kiev, the city was acclaimed by the Soviets as a "Hero City", for the fierce resistance of the Red Army and of the local population. More than 600,000 Soviet soldiers (or one quarter of the Western Front) were killed or taken captive.[31][32]
Initially, the Germans were received as liberators by some Ukrainians, especially in western Ukraine, which had been occupied by the Soviets only in 1939. However, German brutal rule in the occupied territories eventually turned even many of its supporters against the occupation. Nazi administrators of conquered Soviet territories made little attempt to exploit the population of Ukrainian territories' dissatisfaction with Soviet political and economic policies. Instead, the Nazis preserved the collective-farm system, systematically carried out genocidal policies against Jews, deported others (mainly Ukrainians) to work in Germany, and began a systematic depopulation of Ukraine to prepare it for German colonization,[33] which included a food blockade on Kiev. Under these circumstances, most people living in the occupied territory either passively or actively opposed the Nazis.
Total civilian losses inflicted upon the Ukrainian population during the war are estimated between five and eight million,[34][35] including over half a million Jews killed by the Einsatzgruppen, sometimes with the help of local collaborators. Of the estimated 7.5 to 10.6 million Soviet troops who fell in battle and in captivity against the Nazis,[36][37] about a quarter (2.5 million) were ethnic Ukrainians.[34][b] Ukraine is distinguished as one of the first nations to fight the Axis powers in Carpatho-Ukraine, and one that saw some of the greatest bloodshed during the war.