The Eastern Front of World War II was a theatre of conflict between the European Axis powers and co-belligerent Finland against the Soviet Union, Poland and other allies, which encompassed Northern, Southern and Central and Eastern Europe from 22 June 1941 to 9 May 1945. It has been known as the Great Patriotic War (Russian: Великая Отечественная Война, Velikaya Otechestvennaya Voyna) in the former Soviet Union and in modern Russia, while in Germany it was called the Eastern Front (German: die Ostfront), the Eastern Campaign (der Ostfeldzug) or the Russian Campaign (der Rußlandfeldzug).
The battles on the Eastern Front constituted the largest military confrontation in history. They were characterized by unprecedented ferocity, wholesale destruction, mass deportations, and immense loss of life variously due to combat, starvation, exposure, disease, and massacres. The Eastern Front, as the site of nearly all extermination camps, death marches, ghettos, and the majority of pogroms, was central to the Holocaust. Of the estimated 70 million deaths attributed to World War II, over 30 million,
many of them civilian, occurred on the Eastern Front. The Eastern Front was decisive in determining the outcome of World War II, eventually serving as the main reason for Germany's defeat. It resulted in the destruction of the Third Reich, the partition of Germany for nearly half a century and the rise of the Soviet Union as a military and industrial superpower.
The two principal belligerent powers were Nazi Germany and the Soviet Union, along with their respective allies. Though never engaged in military action in the Eastern Front, the United Kingdom and the United States both provided substantial material aid in the form of the Lend-Lease to the Soviet Union. The joint German–Finnish operations across the northernmost Finnish–Soviet border and in the Murmansk region are considered part of the Eastern Front. In addition, the Soviet–Finnish Continuation War may also be considered the northern flank of the Eastern Front.