World War II

Allied designations for the various theaters of operations.

World War II (1931-1945) was the most destructive global war in human history, killing 53 million people. World War II in Asia was foreshadowed by the Japanese invasion of Manchuria in 1931 and began formally with the invasion of China by Japan of 1937. World War II in Europe arguably began with the ascension of Adolf Hitler and the Nazi Party to power in Germany in 1933, although many Western governments did not immediately understand the nature of the growing threat from the Nazis. World War II in Europe also should not be regarded as entirely separate from the Spanish Civil War (1936–39), whose 200,000 fatalities due to systematic murder, mob violence, and torture provided a breeding ground for mass atrocities later committed the Nazis. World War II also included the Holocaust, the state-sponsored murder of 6 million Jews by the Nazis, who also systematically murdered (or placed in camps to die) many more millions of people besides Jews, including political prisoners, Roma, Soviet prisoners of war, homosexuals, criminals, Jehovah’s Witnesses, and handicapped people living in institutions.

With battles in Europe, Africa, Asia and the South Pacific, the "Allies" (led mainly by the UK, US, and Soviet Union) eventually stopped the aggressively expanding "Axis" (mainly Germany and Japan). Hostilities in Europe formally ended after Nazi Germany collapsed in May of 1945. And in August of 1945, the United States destroyed the Japanese cities of Hiroshima and Nagasaki with newly developed atomic bombs, killing around 355,000 civilians and leading to Japan's total surrender.

This war, more than any other, propelled nations towards total war, a complete social, political, military, and economic commitment of a nation to war. Thus the war stimulated unprecedented levels of productivity and generated a wide variety of new technologies. The nations had been mobilized in the interests of many opposing ideologies, often seeking the unconditional surrender of their enemies. As whole populations were materially and politically, if not militarily, invested in the war effort, the distinction between combatant and non-combatant became blurred. Furthermore, many of these ideologies preached ideas of racism and genocide. Thus the level of civilian causalities in this war far surpasses any other in human history.

This war also marks the end of European domination of the globe and the rise of a bi-polar world dominated by two superpowers, the United States and the Soviet Union. The war also broke the ability of the remaining colonial powers (mainly Great Britain, France, Japan, and the Netherlands) to hold and maintain their empires. Thus the war also sparked a period of decolonization afterward. In the Commonwealth nations, official histories of the war use the term Second World War. This style also follows literally translations of other nations' official designation for the conflict, e.g. Zweiter Weltkrieg in German. The official histories of the United States refer to the conflict as World War II or World War Two, and that term is now often used in Canada and the UK as well. Parts of the world, especially Latin America, were largely unaffected directly by the conflict, with significant concentrations of activity in the European, north African, Russian, and Pacific theaters.

Europe

Poland

Germany attacked Poland on September 1, 1939. The German invasion has often been referred to as "blitzkrieg" (lighting war), due to the close coupling of tank-heavy armored forces with close air support, under common radio direction, with foot-mobile infantry following up to secure the breaches.

France and Great Britain, having sworn to defend Poland, declared war on Germany but in the end were unable to provide material assistance. The Soviet Union launched its own invasion of Polish territory, and Slovak troops also participated in operations on Polish soil. Poland officially capitulated in October.

Western Front

Phoney War

Invasion of Norway

Battle for France and the Low Countries

Battle of Britain

Battle of the Atlantic

Invasion of Normandy

Northwest Europe Campaign

Southern France

Crossing the Rhine

Mediterranean Front

Invasion of Greece

Invasion of Yugoslavia

North Africa

Battle of Sicily

Italian Campaign

Eastern Front

Winter War

Operation Barbarossa

Continuation War

Battle of Berlin

Asia

see World War II in the Pacific

China, Burma, and India

see CBI

Second Sino-Japanese War

Japanese expansion in the Pacific

Battle of Pearl Harbor

Battle of Midway

Battle of Coral Sea

Battle of Guadalcanal

Defeat of the Japanese Empire

Battle of the Philippine Sea

Battle of Leyte Gulf

Battle of Iwo Jima

Battle of Okinawa

Naval Warfare

Major developments

(PD) Photo: United States Navy
U.S.S. Massachusetts (BB-59) underway at 15 knots off Point Wilson, Washington on July 11, 1944.

(PD) Photo: United States Navy
The aircraft carrier U.S.S. Enterprise (CV-6) at sea, circa 1943-44.

On December 7, 1941, the battleship, with large guns as its primary weapon, had become secondary to the aircraft carrier as the dominant ship of the world's navies. The last combat between battleships was the Battle of Surigao Strait on October 25, 1944.

Naval aviation, primarily carrier-based but with some significant activity by land-based aircraft, became the centerpiece of combat at sea, although submarines (primarily operating alone) also proved to be decisive. Defense against aircraft attack also advanced quickly, with the key technologies of radar, improved anti-aircraft artillery with proximity-fuzed shells, combat air patrol doctrine, and combat information center coordination. Defense was especially important against the first large-scale use of precision-guided munitions, or kamikaze aircraft with pilots intending to die with their airplanes crashing into ships.

Amphibious warfare doctrine and practice constantly improved.

Replenishment at sea allowed U.S. fleets to operate for long periods, away from bases. This was a major force multiplier.

Air War

see World War II, air war

Results and Aftermath

Japan

Total Japanese military fatalities between 1937 and 1945 were 2.1 million; most came in the last year of the war. Starvation or malnutrition-re­lated illness accounted for roughly 80 percent of Japanese military deaths in the Philippines, and 50 percent of military fatalities in China. The aerial bombing of a total of 65 Japanese cities appears to have taken a minimum of 400,000 and possibly closer to 600,000 civilian lives (over 100,000 in Tokyo alone, over 200,000 in Hiroshima and Nagasaki combined, and 80,000-150,000 civilian deaths in the battle of Okina­wa). Civilian deaths among settlers who died attempting to re­turn to Japan from Manchuria in the winter of 1945 were probably around 100,000.