The Eastern Front, also called the Soviet-German War or the Great Patriotic War, was a theatre of World War II fought between the Nazi German-led Axis Powers and the Soviet-led Eastern Allies. The theatre opened with a surprise German invasion of the USSR, Operation Barbarossa, and resulted in four years of brutal combat that left 30 million people dead, including 9 million children.
More than 80% of all combat during World War II took place on the Eastern Front, where the Germans and their allies invaded the USSR along a 1,800-mile front, reached the gates of Moscow and the steppes of the North Caucasus, and were gradually driven back into the Baltics, Poland, and the Balkans by the Red Army. During the German invasion of the Soviet Union, the German military engaged in vicious brutality, scorched-earth tactics, wanton destruction, mass deportations, forced starvations, wholesale terrorism, and massacres, overseeing genocidal campaigns with the goal of exterminating more than 100 million Eastern European natives to make way for the German settlement of Europe up to the Urals. German Einsatzgruppen followed the advancing Wehrmacht forces, systematically executing Jewish civilians along the way; the German army also engaged in the summary execution of Soviet commissars and prisoners as part of national socialism's war of annihilation against Bolshevik communism. The German invasion of the USSR was aided by Soviet collaborators, including the Russian Liberation Army, the Ukrainian Liberation Army, the Georgian Legion, and the Ostlegionen, while Soviet citizens helped form the Latvian Legion and 14th Waffen Grenadier Division of the SS (1st Galician). The Organization of Ukrainian Nationalists (OUN), a Ukrainian ultranationalist and anti-communist movement inspired by Benito Mussolini's National Fascist Party, initially collaborated with the Nazis, helping round up Jews for extermination and recruiting collaborators for the German auxiliary police. In 1942, however, the OUN turned against the Nazis on realizing that the Germans would not establish a Ukrainian puppet government, and they formed the Ukrainian Insurgent Army to fight against both the Nazis and the Soviets. From 1943 to 1945, they would be responsible for the "Volyn Tragedy", in which they massacred up to 120,000 Poles and 340 Czechs in the Volhynia and Eastern Galicia borderlands in a move to prevent Poland from erasserting its sovereignty over the region after the war.
The Soviet victory at the Battle of Moscow in December 1941 halted the German invasion of Russia in the north, while the northern Soviet city of Leningrad withstood a brutal siege until 1944. From September 1942 to January 1943, the German 6th Army attempted to capture the southern Russian city of Stalingrad and push into the Caucasus, but the 6th Army was surrounded and forced to surrender after months of brutal fighting, marking the first occasion in which a German army surrendered during the war. The Soviets began a slow and bloody process of evicting the Germans from the USSR, fighting in the Crimea, Ukraine, and western Russia. The Axis defeat at the Battle of Kursk in August 1943 terminated Germany's offensive strength in the East, clearing the way for the Soviets to push the Germans out of their "motherland." In November 1943, the Soviets liberated Kyiv, and, from December 1943 to May 1944, the Dnieper-Carpathian Offensive drove the Germans out of right-bank Ukraine and enabled the Soviets to prepare for a massive offensive to finally drive the Axis Powers from Russian soil.
The Soviets' Operation Bagration in the summer of 1944 resulted in the destruction of German Army Group Center in Belarus and the liberation of much of the Baltics, while the threat of a Soviet invasion of the Balkans led Romania and Bulgaria to defect to the Soviet side, Bulgaria without any fighting. At the same time, Finland - which had successfully fought off a Soviet invasion in the Winter War of 1939-1940 and sided with the Germans in the Continuation War with the USSR - made peace with the USSR and soon allied with the Soviets to expel the German forces occupying Lapland in the Lapland War.
Following the success of Bagration, Soviet forces in the Balkans joined with the Bulgarians and the Yugoslav Partisans to liberate Belgrade and other major Yugoslav cities from the Germans, while Soviet forces pushed into Hungary and captured Budapest in February 1945. Warsaw was liberated in January 1945 as the Soviets pushed into Poland and East Prussia, and the Prussian city of Koenigsberg fell to the Soviets on 9 April 1945, ending over 700 years of Germanic rule in the region.
The spring of 1945 saw the Soviets launch offensives against Berlin and Vienna, taking Vienna on 15 April 1945 and Berlin on 2 May. As the war came to a close, the Soviets pushed into Czechoslovakia, taking the Slovakian capital of Bratislava on 4 April, the Moravian capital of Brno on 25 April-5 May 1945, and Prague on 11 May. By then, Adolf Hitler's suicide, the meeting of the Soviet and Western Allied armies along the Elbe River, and the confining of Germany's Eastern Front forces to Austria, Bohemia and Moravia, Courland, Pomerania, Silesia, and Poland's Hel Peninsula forced the German head of state Karl Doenitz to agree to Germany's capitulation on 8 May 1945.
The fighting on the Eastern Front involved up to 3,933,000 Axis troops by 1943 and 6,800,000 Soviet troops by 1944, and historians called the Eastern Front "the most atrocious war of conquest, enslavement, and annihilation known to modern history" and "more gruelling and destructive" than any other theatre of the war. 4.5 million Axis soldiers were killed or went missing in action (3,637,000 Germans, 215,000 Soviet collaborators, 226,000 Romanians, 245,000 Hungarians, 55,000 Italians, and 62,731 Finns), while 4.5 million were captured (3 million+ Germans, 400,000 Soviet collaborators, 500,000 Romanians, 500,000 Hungarians, 70,000 Italians, and 3,500 Finns), 600,000 of whom died in captivity. The Eastern Allies lost up to 10 million killed in action (including at least 6,829,600 Soviet troops, 24,000 Poles, 17,000 Romanians, and 10,000 Bulgarians) and 3.3 million who died in captivity (out of 4.1 million prisoners). Over 11.4 million Soviet civilians were killed, while another 3.5 million were killed in the German-annexed territories in the Baltics, Poland, and Bessarabia. The Nazis exterminated up to 2 million Soviet Jews as part of the Holocaust. By November 1944, the Germans lost wel over 42,700 tanks, tank destroyers, self-propelled guns, and assault guns on the Eastern Front, while the Soviets lost 96,500, as well as 37,600 other armored vehicles for a total of 134,100 armored vehicles lost. The Germans lost 75,700 aircraft, whil the Soviets lost 102,600, including 46,100 in combat.