World War II

World War II was a global conflict fought from 1939 to 1945, involving most of the world's nations in two broad camps: the Allies and the Axis. It was the deadliest war in history, with an estimated 50 to 80 million deaths, and it reshaped international politics, technology, and society for generations.

The war grew out of unresolved tensions from World War I, the harsh peace settlement that followed, the Great Depression, and the aggressive expansion of fascist regimes in Germany, Italy, and Japan.

Causes and the outbreak

In Germany, the Nazi Party led by Adolf Hitler came to power in 1933, promising to overturn the Treaty of Versailles and expand German territory. Italy under Benito Mussolini and militarist Japan pursued their own expansion. The League of Nations proved unable to stop them as Japan invaded Manchuria, Italy invaded Ethiopia, and Germany remilitarised the Rhineland and annexed Austria and part of Czechoslovakia.

Britain and France initially followed a policy of appeasement, hoping to avoid another war. That ended when Germany invaded Poland on 1 September 1939, and Britain and France declared war two days later. The Soviet Union and Germany had secretly agreed to divide eastern Europe, and the USSR invaded Poland from the east soon after.

Axis advances and blitzkrieg

Germany's fast "blitzkrieg" tactics — combining tanks, motorised infantry, and air support — overran much of Europe in 1940, including Denmark, Norway, the Low Countries, and France. Britain survived a major air campaign, the Battle of Britain, and continued to fight. In 1941 Germany invaded the Soviet Union, opening the vast Eastern Front, where fighting was on an enormous scale.

Japan, meanwhile, expanded into China and Southeast Asia, and in December 1941 attacked the United States naval base at Pearl Harbor, bringing America into the war and widening it to the Pacific.

Turning points

The tide turned through several decisive battles. In the Pacific, the Battle of Midway in 1942 checked Japanese expansion. In North Africa, the Battle of El Alamein halted Axis advances. On the Eastern Front, the Soviet victory at Stalingrad in early 1943 and the huge tank battle at Kursk marked the beginning of Germany's retreat.

The Allies then fought back on land, sea, and in the air. A combined Anglo-American force landed in North Africa and later in Italy. On 6 June 1944, "D-Day," Allied troops landed in Normandy and began liberating western Europe. In the Pacific, the United States advanced island by island toward Japan.

The end of the war

Germany surrendered in May 1945 after the fall of Berlin. Japan fought on but, after the atomic bombings of Hiroshima and Nagasaki in August 1945 and the Soviet declaration of war, surrendered in September 1945. The atomic bombs introduced a new and terrifying era in warfare.

The Holocaust and civilian suffering

The war was marked by atrocities on an enormous scale. Nazi Germany carried out the systematic murder of about six million Jews, known as the Holocaust, alongside the killing of Roma, disabled people, political opponents, and others. Occupation, forced labour, and mass displacement affected millions across Europe and Asia. These crimes led to the postwar concepts of genocide and, later, the Universal Declaration of Human Rights.

Aftermath and legacy

Germany and Japan were occupied and rebuilt as democracies. Europe was divided between East and West, and the United States and Soviet Union emerged as rival superpowers, beginning the Cold War. The United Nations was founded in 1945 to prevent future world wars. The war also accelerated decolonisation, as weakened European empires lost control of overseas territories.

Scientific and technological change was profound, from radar and jet aircraft to penicillin and early computing. The war also prompted the creation of international financial institutions and, later, European integration as a way to prevent renewed conflict.

Key points