War is declared in an effort to protect Poland.
Soviet Union and Germany signed a nonaggression pact before the war, and the Soviets are attacking due to the partnership of Stalin and Hitler.
Warsaw surrenders on September 27. The Polish government flees into exile via Romania. Germany and the Soviet Union divide Poland among themselves.
The Soviet Union invades Finland.
Denmark surrenders the day of the attack while Norway holds out until June 9th.
Germany attacks western Europe—France and the neutral Low Countries. Luxembourg is occupied on May 10; the Netherlands surrenders on May 14; and Belgium surrenders on May 28. On June 22, France signs an armistice agreement by which the Germans occupy the northern half of the country and the entire Atlantic coastline. In southern France, a collaborationist regime with its capital in Vichy is established.
The air war, Battle of Britain, ends in defeat for Germany.
Germany, Italy, and Japan sign the Tripartite Pact.
Slovakia (November 23), Hungary (November 20), and Romania (November 22) join the Axis.
The leaders of the terrorist Ustasa movement proclaim the so-called Independent State of Croatia. Recognized immediately by Germany and Italy, the new state includes the province of Bosnia-Herzegovina. Croatia joins the Axis powers formally on June 15, 1941.
Nazi Germany and its Axis partners (except Bulgaria) invade the Soviet Union. Finland, seeking redress for the territorial losses in the armistice concluding the Winter War, joins the Axis just before the invasion. The Germans quickly overrun the Baltic States and, joined by the Finns, lay siege to Leningrad (St. Petersburg) by September. In the center, the Germans capture Smolensk in early August and drive on Moscow by October. In the south, German and Romanian troops capture Kiev (Kyiv) in September and capture Rostov on the Don River in November.
A Soviet counteroffensive drives the Germans from the Moscow suburbs in chaotic retreat.
The U.S. Declares war on Japan, therefore, entering the war as an Ally country.
The British bomb Köln (Cologne), bringing the war home to Germany for the first time. Over the next three years Anglo-American bombing reduces urban Germany to rubble.
British and US navies halt the Japanese naval advance in the central Pacific at Midway.
British troops defeat the Germans and Italians at El Alamein in Egypt, sending the Axis forces in chaotic retreat across Libya to the eastern border of Tunisia.
Soviet troops counterattack, breaking through the Hungarian and Romanian lines northwest and southwest of Stalingrad and trapping the German Sixth Army in the city. Forbidden by Hitler to retreat or try to break out of the Soviet ring, the survivors of the Sixth Army surrender on January 30 and February 2, 1943.
US and British troops land on Sicily. By mid-August, the Allies control Sicily.
The Fascist Grand Council deposes Benito Mussolini, enabling Italian marshall Pietro Badoglio to form a new government.
The Badoglio government surrenders unconditionally to the Allies. The Germans immediately seize control of Rome and northern Italy, establishing a puppet Fascist regime under Mussolini, who is freed from imprisonment by German commandos on September 12.
Soviet troops liberate Kiev.
British and US troops successfully land on the Normandy beaches of France, opening a “Second Front” against the Germans.
Allied troops reach Paris. On August 25, Free French forces, supported by Allied troops, enter the French capital. By September, the Allies reach the German border; by December, virtually all of France, most of Belgium, and part of the southern Netherlands are liberated.
The Germans launch a final offensive in the west in an attempt to re-conquer Belgium and split the Allied forces along the German border. By January 1, 1945, the Germans are in retreat.
The Soviets launch their final offensive, encircling Berlin.
Adolf Hitler commits suicide.
U.S. Counterattack After Pearl Harbor Bombing
August 6: Atomic Bomb on Hiroshima
August 9: Atomic Bomb on Nagasaki
The Soviet Union declares war on Japan and invades Manchuria.
Having agreed in principle to unconditional surrender on August 14, 1945, Japan formally surrenders, ending World War II.