Invasions of Poland by Germany, beginning World War II. Most of Poland is taken in days.
Germany invades Denmark, Norway, France, the Netherlands, Belgium, Luxembourg. All fall within weeks
Germany suffers its first defeat in the skies over England, and abandons invasion plans.
British armored forces attack Italian forces in North Africa. This continues for nearly three years.
June, Germany invades the USSR, opening what becomes known as the Eastern Front.
December 7, the Imperial Japanese Navy attacks the US Pacific Fleet anchored at Pearl Harbor, Hawaii. US enters the war, opening the Pacific Theatre.
June 4-7, Battle of Midway. The US Navy sinks four Japanese aircraft carriers in the fight that proves to be the turning point in the Pacific war.
Battle of Stalingrad. Germany's entire Sixth Army is lost, and the war begins turning in favor of the Allies.
Several failed assassination attempts on Hitler's life. Hitler has become too unstable to think rationally. Succession of major military losses follows.
June 6, the Allied Expeditionary Force under Dwight Eisenhower lands on the coast of northern France on what will later be called "D-Day". The "Second Front" that Stalin has been demanding for three years is now open.
April 30, Hitler commits suicide, shortly before the fall of Berlin and surrender of German forces in Europe.
USA develops the atomic bomb, and successfully uses it in August to force the surrender of Japan.