This event is important because it marked the official beginning of World War II, one of the deadliest and most devastating conflicts in human history. The invasion of Poland by Germany on September 1, 1939, prompted the Allied powers, including Great Britain and France, to declare war on Germany just days later. This event also led to the eventual involvement of other major powers, including the United States and the Soviet Union, in the war. The invasion of Poland resulted in widespread death and destruction and set off a series of events that had far-reaching consequences for the world.
