1939年9月1日，德國以閃電戰進攻波蘭，第二次世界大戰正式開始，隨後迅速占領了丹麥、挪威、荷蘭、比利時和盧森堡等國。1940年，擊敗英法聯軍，並占領了法國。隨後占領了南斯拉夫和希臘等國。
1941年6月22日，德國開始進攻蘇聯。1942年鼕，斯大林格勒戰役開始，德軍失利，成為第二次世界大戰的轉折點。
1944年6月6日，美英聯軍在法國諾曼底登陸，1945年5月8日德國宣佈無條件投降。第二次世界大戰結束後，根據雅爾塔協定，蘇美英法分區占領德國，柏林作為特殊單位由4國共同管理。1949年5月，美、英、法3國占領區合併，成立德意志聯邦共和國，同年10月，蘇聯占領區宣佈成立德意志民主共和國，德國分裂為兩個國傢。
The history of Germany during World War II closely parallels that of Nazi Germany under Adolf Hitler. Adolf Hitler came to power in Germany in 1933. From that point onward, Germany followed a policy of rearmament and confrontation with other countries. During the war German armies occupied most of Europe; Nazi forces defeated France, took Norway, invaded Yugoslavia and Greece, and occupied much of the European portion of the Soviet Union. Germany also forged alliances with Hungary, Romania, Bulgaria, and later Finland, as well as collaborators in several other nations. The German defeat at the Battle of Stalingrad in 1942 was considered the decisive victory that turned the tide of the war against Germany and her Anti-Cominterm allies. The Second World War culminated in Germany's unconditional surrender to the Allies, the fall of Nazi Germany, and the death of Adolf Hitler.