Soviet invasion of Poland was a Soviet military operation that started without a formal declaration of war on 17 September 1939, during the early stages of WWII. 16 days after Nazi Germany invaded Poland from the West, the Soviet Union did so from the East. The invasion ended on 6 October 1939 with the division and annexing of the whole of the 2nd Polish Republic by Germany and The USSR.
World War II: The Invasion of Poland and the Winter War
At 4.45 am on 1 September 1939 the German battleship Schleswig-Holstein opened fire on the Polish garrison of the Westerplatte Fort, Danzig (modern-day Gdansk), in what was to become the first military engagement of World War Two. Simultaneously, 62 German divisions supported by 1,300 aircraft commenced the invasion of Poland. The decision of Adolf Hitler to invade Poland was a gamble.
The Invasion of Poland, also known as the September Campaign or 1939 Defensive War in Poland and the Poland Campaign (German: Polenfeldzug) in Germany, was an invasion of Poland by Germany, the Soviet Union, and a small Slovak contingent that marked the start of World War II in Europe. The invasion began on 1 September 1939, one week after the signing of the Molotov–Ribbentrop Pact, and ended on 6 October 1939 with Germany and the Soviet Union dividing and annexing all of Poland.
A young Polish boy returns to what was his home and squats among the ruins during a pause in the German air raids on Warsaw, Poland, in September of 1939. German attacks lasted until Warsaw surrendered on September 28. One week later, the last of the Polish forces capitulated near Lublin, giving full control of Poland to Germany and the Soviet Union. (AP Photo/Julien Bryan)