On September 1, 1939, German forces launched a combined air and ground assault on Poland, employing blitzkrieg tactics — coordinated bombing followed by rapid armored advances. The Luftwaffe destroyed the Polish air force within days. Germany had staged a false-flag attack on the Gleiwitz radio station the night before as a pretext. Britain and France declared war on Germany on September 3. On September 17, the Soviet Union invaded Poland from the east per the Molotov-Ribbentrop Pact's secret protocol. Polish resistance ended by October 5, and the country was partitioned between the two invaders.