Good stamps. German armies invaded the Soviet Union on 22 June 1941, initiating nearly four years of total war. The Axis initially advanced against desperate but unsuccessful efforts of the Red Army. In the encirclement battle of Kiev, the city was acclaimed as a "Hero City", because of its fierce resistance. More than 600,000 Soviet soldiers (or one-quarter of the Soviet Western Front) were killed or taken captive there, with many suffering severe mistreatment. Although the majority of Ukrainians fought in or alongside the Red Army and Soviet resistance, in Western Ukraine an independent Ukrainian Insurgent Army movement arose (UPA, 1942). Created as forces of the Ukrainian Government in exile, it fell under the influence of the underground (Organization of Ukrainian Nationalists, OUN) which had developed in interwar Poland as a radical reaction to Polish policies towards the Ukrainian minority. Both supported the goal of an independent Ukrainian state on the territory with a Ukrainian ethnic majority. Although this brought conflict with Nazi Germany, at times the Melnyk wing of the OUN allied with the Nazi forces. Some UPA divisions also carried out massacres of ethnic Poles, which brought reprisals. After the war, the UPA continued to fight the USSR until the 1950s. At the same time, the Ukrainian Liberation Army, another nationalist movement, fought alongside the Nazis.In total, the number of ethnic Ukrainians who fought in the ranks of the Soviet Army is estimated from 4.5 million to 7 million. The pro-Soviet partisan guerrilla resistance in Ukraine is estimated to number at 47,800 from the start of occupation to 500,000 at its peak in 1944, with about 50% being ethnic Ukrainians. Generally, the Ukrainian Insurgent Army's figures are unreliable, with figures ranging anywhere from 15,000 to as many as 100,000 fighters