German soldiers hid in the trenches where the dead bodies of the dead and wounded were strewn about as the Germans fought in the capital, Warsaw. The capital Warsaw fell on September 27, 1939. The Germans lost 8,082 dead and were defeated in about four weeks.

 　　World War II broke out with the German invasion of Poland on September 1, 1939; by September 19, the Polish army was surrounded by German troops and some 20,000 Polish soldiers were killed in action. The Germans fought in the capital city of Warsaw during the invasion, where German soldiers hid themselves in trenches littered with the corpses of the dead and wounded. The capital Warsaw fell on September 27, 1939, and the last traces of resistance were gone by October 5, 1939. The Germans lost 8,082 dead in the campaign, and the invading Germans defeated the Polish army in about four weeks.

　　The final collapse of Poland was accelerated by the Soviet Red Army's invasion and occupation of its eastern territories on September 17. The German-Soviet Pact divided Poland in two with the Soviet Union, giving the Soviets free rein in the Baltic Sea. German casualties in the invasion of Poland were 27,278 killed and 5029 missing, while Polish casualties were 70,000 killed and 130,000 wounded. The swiftness of the operation and the low German casualties were also the result of the Soviet Red Army's invasion of eastern Poland.

　　On September 3, 1939, both Great Britain and France, which had signed mutual defense treaties with Poland, declared war on Germany after Germany did not respond to an ultimatum demanding immediate and unconditional withdrawal from Polish territory. World War II became an unequal battle from the outset. The Germans organized an army of about 1.5 million men for the invasion and attack on Poland, with 2,750 tanks, 2,315 fighter planes, and 9,000 artillery guns. The Polish army had 1 million troops, but could not mobilize many of them. Even those that could be mobilized were equipped with outdated equipment, with only 4,300 guns, 210 tanks, 670 tankettes, and 800 fighter planes. Poland was planned to attack Germany from the west by France and Great Britain, who had signed a military alliance on March 31. The Polish army was mistakenly overrun by the Germans without the Allied forces coming to Poland's aid.