The Second World War officially began on 1 September 1939, with the German invasion of Poland. Britain and France declared war on the Third Reich on 3 September 1939. Seven days later, on 10 September 1939, the Parliament of Canada likewise declared war on Germany, the country's first independent declaration of war and the beginning of Canada's participation in the largest combined national effort in its history. By war's end, over 1 million citizens would serve in military uniform, and Canada would possess the fourth-largest air force and third-largest naval surface fleet in the world.