Answer: The European theatre of World War II was one of the two main theatres of combat[nb 19] during World War II. It saw heavy fighting across Europe for almost six years, starting with Germany's invasion of Poland on 1 September 1939 and ending with the Western Allies conquering most of Western Europe, the Soviet Union conquering most of Eastern Europe and Germany's unconditional surrender on 8 May 1945[nb 20] although fighting continued elsewhere in Europe until 25 May. On 5 June 1945, the Berlin Declaration proclaiming the unconditional surrender of Germany to the four victorious powers was signed. The Allied powers fought the Axis powers on two major fronts (Eastern Front and Western Front) as well as in a strategic bombing offensive and in the adjoining Mediterranean and Middle East theatre.