World War II

World War II, also called the Second World War, lasted from 1 September 1939 to 2 September 1945. It was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries took part, and many of them fought in total war on a scale never seen before. It was the deadliest conflict in history, and it caused the deaths of many millions of people, most of them ordinary civilians. Many people were harmed in terrible events, including genocides and the Holocaust. After the Allies won, Germany, Austria, and Japan were occupied, and Korea was freed from Japanese rule and divided into occupation zones. German and Japanese leaders were put on trial for war crimes.

The causes of World War II included problems left over from the aftermath of World War I and the rise of fascism in Europe and militarism in Japan. Earlier events included Japan's invasion of Manchuria in 1931, the Spanish Civil War, the start of the Second Sino-Japanese War in 1937, and Germany's annexations of Austria and the Sudetenland. The war is generally said to have begun on 1 September 1939, when Nazi Germany, led by Adolf Hitler, invaded Poland. The United Kingdom and France declared war on Germany. The Soviet Union also moved into Poland in mid-September, and the country was divided between the two states under the Molotov–Ribbentrop Pact. In 1940, the Soviet Union annexed the Baltic states, parts of Finland, and Romania. Germany conquered Norway, Denmark, Belgium, Luxembourg, and the Netherlands. After the fall of France in June 1940, the war continued mainly between Germany, now helped by Fascist Italy, and the British Empire and British Commonwealth. Fighting took place in the Balkans, the Mediterranean, Middle East, East Africa, in the skies during the Battle of Britain and the Blitz, and at sea in the Battle of the Atlantic. By mid-1941, Yugoslavia and Greece had also been defeated by Axis countries. In June 1941, Germany invaded the Soviet Union, which opened the Eastern Front.

In December 1941, Japan attacked American and British territories in Asia and the Pacific, including Pearl Harbor in Hawaii. This led the United States to join the war against the Axis. Japan took much of coastal China and Southeast Asia, but its advances in the Pacific were stopped in June 1942 at the Battle of Midway. In early 1943, Axis forces lost in North Africa and at Stalingrad in the Soviet Union. An Allied invasion of Italy in July led to the fall of its fascist regime. Allied attacks in the Pacific and the Soviet Union pushed the Axis to retreat on all fronts. In 1944, the Western Allies invaded France at Normandy, opening a new front, and the Soviet Union moved forward into Central Europe. Japan also suffered major setbacks, including the weakening of its navy by the United States, the loss of key islands in the Western Pacific, and defeats in Burma.

The war in Europe ended as German-occupied territories were freed and Allied forces entered Germany itself. This led to the fall of Berlin and Germany's unconditional surrender on 8 May 1945. On 6 and 9 August, the United States dropped atomic bombs on Hiroshima and Nagasaki. This was followed by a Soviet invasion of Japanese-occupied Manchuria. Japan announced its unconditional surrender on 15 August and signed a surrender document on 2 September 1945.

World War II changed the political, economic, and social structures of the world. It set the foundations for international relations for the rest of the 20th century and into the 21st century. The United Nations was created to encourage countries to work together and to help prevent future wars. The victorious great powers, China, France, the Soviet Union, the United Kingdom, and the United States, became the permanent members of its Security Council. The Soviet Union and the United States became rival superpowers, which set the stage for the Cold War. After the destruction in Europe, the influence of its great powers faded. This led to the decolonisation of Africa and of Asia. Many countries whose industries had been damaged moved towards economic recovery and expansion. Several terms redirect here. For other uses, see WWII (disambiguation), The Second World War (disambiguation), and World War II (disambiguation).

Start and end dates

See also: List of timelines of World War II

Most historians agree that World War II began when the German invasion of Poland took place on 1 September 1939. Two days later, the British and French declared war on Germany. Some people say the Pacific War started with the Second Sino-Japanese War on 7 July 1937. Others point to the earlier Japanese invasion of Manchuria on 18 September 1931. Another possible starting date is the Italian invasion of Abyssinia on 3 October 1935. The British historian Antony Beevor sees the start in the Battles of Khalkhin Gol. These fights took place between Japan and the forces of Mongolia and the Soviet Union from May to September 1939. Some people see the Spanish Civil War as the start of the war, or as something that led to it.

Not everyone agrees on when the war ended. At the time, most people accepted that the war ended with an armistice (an agreement to stop fighting) on 15 August 1945, known as V-J Day. The formal surrender of Japan came on 2 September 1945. This officially ended the war in Asia. A peace treaty between Japan and the Allies was signed in 1951. A 1990 treaty regarding Germany's future allowed the reunification of East and West Germany to happen. No formal peace treaty between Japan and the Soviet Union was ever signed. However, the Soviet–Japanese Joint Declaration of 1956 ended the state of war between the two countries. It also restored full diplomatic relations between them.

Background

Main article: Causes of World War II

After World War I ended, the map of Europe changed a lot. The Central Powers each lost land in the peace treaties. New nation-states were formed from the Austro-Hungarian, Ottoman, and Russian Empires. To help prevent another world war, the League of Nations was set up in 1920 by the Paris Peace Conference. Its main job was to stop fighting through shared safety, naval disarmament, and peaceful talks. Many people wanted peace after World War I. However, irredentist and revanchist nationalism grew in several European countries. This was strongest in Germany, which lost land, its colonies, and money under the Treaty of Versailles. Germany lost part of its home land and its overseas possessions. It was also not allowed to take over other countries, had to pay reparations, and had limits placed on its armed forces. The German Empire ended in the German revolution of 1918–1919, and a democratic government, later known as the Weimar Republic, was created. The interwar period saw conflict between supporters of the new republic and extreme groups on both the right and left.

Italy had gained some land after the war as an entente ally. However, Italian nationalists were angry that the promises made to bring Italy into the war were not kept. From 1922 to 1925, the fascist movement led by Benito Mussolini took power in Italy. It was totalitarian, meaning the government controlled almost everything. It had a nationalist and class collaborationist agenda. It ended representative democracy, shut down socialist, left-wing, and liberal groups, and promised a "New Roman Empire".

Adolf Hitler tried and failed to overthrow the German government in 1923. In 1933, President Paul von Hindenburg and the Reichstag appointed him chancellor of Germany. The Nazis soon ended parliamentary democracy. They pushed a radical, racially motivated revision of the world order and began a large rearmament campaign. After Hindenburg died in 1934, Hitler named himself Führer of Germany. France, wanting to keep its alliance with Italy, allowed Italy a free hand in Ethiopia, a colony Italy wanted. In early 1935, the Territory of the Saar Basin was reunited with Germany.

Hitler then rejected the Treaty of Versailles, sped up his rearmament, and introduced conscription. That April, the United Kingdom, France, and Italy formed the Stresa Front to contain Germany. This was a key step towards military globalisation. That June, though, the United Kingdom made an independent naval agreement with Germany that eased earlier limits. The Soviet Union was worried about Germany's goals of capturing vast areas of Eastern Europe. It drafted a treaty of mutual help with France. The Franco-Soviet pact had to go through the League of Nations first, which made it weak. The United States passed the Neutrality Act that August.

In March 1936, Hitler broke the Versailles and Locarno Treaties by remilitarising the Rhineland. He faced little opposition because of appeasement. In October 1936, Germany and Italy formed the Rome–Berlin Axis. A month later, Germany and Japan signed the Anti-Comintern Pact, which Italy joined the next year.

In China, the Kuomintang party launched a unification campaign against regional warlords. It nominally unified China in the mid-1920s. Soon after, it fell into a civil war against its former Chinese Communist Party allies and new regional warlords. In 1931, the increasingly militaristic Empire of Japan wanted influence in China as a step toward its right to rule Asia. It staged the Mukden incident as an excuse to invade Manchuria. Then it set up the puppet state of Manchukuo. After Japan was condemned by the League of Nations, it left the League. The two nations fought battles in Shanghai, Rehe, and Hebei until the Tanggu Truce was signed in 1933. Chinese volunteer forces kept resisting in Manchuria and Chahar and Suiyuan. After the 1936 Xi'an Incident, the Kuomintang and CCP agreed to a ceasefire. They wanted to present a united front against Japan.

Pre-war events

Main article: Second Italo-Ethiopian War

Main article: Spanish Civil War

Main article: Second Sino-Japanese War

Main article: Soviet–Japanese border conflicts

The Second Italo-Ethiopian War was a colonial war that began in October 1935 and ended in May 1936. Italian forces came from Italian Somaliland and Eritrea and invaded the Ethiopian Empire, which was also called Abyssinia. Ethiopia came under military occupation and was joined to the new colony of Italian East Africa. The war showed that the League of Nations was weak. The League did very little, even though Italy clearly broke Article X of the League's Covenant. When a civil war broke out in Spain, Hitler and Mussolini supported the Nationalist rebels, led by General Francisco Franco. Italy sent more troops and planes than Germany did. The Soviet Union supported the Spanish Republic, and more than 30,000 foreign volunteers in the International Brigades fought the Nationalists. Germany and the Soviet Union used this proxy war to test their weapons and tactics. The Nationalists won in April 1939. Franco stayed officially neutral in World War II but generally favoured the Axis, sending volunteers to fight on the Eastern Front.

In July 1937, Japan captured the former Chinese imperial capital of Peking after the Marco Polo Bridge incident. This came after years of tension and low-level conflicts, and it led to a campaign to invade all of China. The Soviets signed a non-aggression pact with China to give materiel support, which ended China's prior cooperation with Germany. Japan attacked Taiyuan, fought the Kuomintang Army around Xinkou and communist forces in Pingxingguan, and took control of China's northern railways. Nationalist Generalissimo Chiang Kai-shek sent his best army to defend Shanghai. After three months of hard fighting, the city fell. Japan then went on capturing the capital Nanking in December 1937. In March 1938, Nationalist forces won their first major victory at Taierzhuang. However, they ultimately lost control of the city of Xuzhou in May. In June 1938, Chinese forces slowed Japan by flooding the Yellow River, which caused great harm to local people. Even so, the city was taken at Wuhan by October. Japanese victories did not break Chinese resistance, and the government moved inland to Chongqing. Japanese aircraft then began striking cities in the Sichuan basin in a bombing campaign that caused great harm to many civilians.

In the mid-to-late 1930s, Japanese forces in Manchukuo had occasional border clashes with the Soviet Union and Mongolia. The Hokushin-ron idea, which favoured expansion northward, was supported by the Imperial Army. However, Japan was defeated at Khalkin Gol in 1939. The ongoing Sino-Japanese War and Nazi Germany's neutrality toward the Soviets also made it hard to keep this plan. Japan and the Soviet Union signed a Neutrality Pact in April 1941. Japan then adopted Nanshin-ron, promoted by the Navy, which turned its focus southward. This eventually led to war with the United States and the Western Allies.

In Europe, Germany and Italy grew more aggressive. In March 1938, Germany annexed Austria, again with little response from others. Hitler then pressed claims on the Sudetenland, an area of Czechoslovakia with a mostly ethnic German population. The United Kingdom and France followed the appeasement policy of British Prime Minister Neville Chamberlain. They gave this territory to Germany in the Munich Agreement, even though the Czechoslovak government did not want this. In March 1939, Germany invaded the remainder of Czechoslovakia and split it into the Protectorate of Bohemia and Moravia and a pro-German client state, the Slovak Republic. When Italy conquered Albania in April 1939, the United Kingdom and France guaranteed their support for Polish independence, and this promise was extended to the Kingdoms of Romania and Greece. Germany and Italy also formed the Pact of Steel. On 23 August, the Soviet Union signed a non-aggression pact with Germany. This agreement included a secret plan to divide Bessarabia and Poland between them. Germany offered Britain an alliance, but Britain replied that it would keep its promise to Poland. On the night of 30–31 August, British ambassador Nevile Henderson met German Foreign Minister Joachim von Ribbentrop. Ribbentrop handed him Hitler's demands regarding Poland, and then announced that the deadline for Poland to accept had already passed.

For a chronological guide, see List of timelines of World War II.

See also: Diplomatic history of World War II and World War II by country

Main article: European theatre of World War II

Main article: Western Front (World War II)

Main article: Eastern Front (World War II)

Main article: Pacific War

On 1 September 1939, Germany invaded Poland, and on 3 September, Britain and France declared war on Germany. In 1940, Germany invaded Denmark and Norway, then attacked France. France signed an armistice with Germany that June. The Battle of Britain followed, with German bombing of British cities in the Blitz. On 22 June 1941, Germany invaded the Soviet Union in Operation Barbarossa. On 7 December 1941, Japan attacked Pearl Harbor, and the United States entered the war. In 1942 and 1943, the Axis advance was stopped. The Allies won a decisive victory at Midway, and the Germans were defeated at Stalingrad. The Soviets then gained the upper hand after the Battle of Kursk. In September 1943, the Western Allies invaded the Italian mainland.

On 6 June 1944, known as D-Day, the Western Allies invaded northern France. Soviet forces pushed back the Germans in the east, and in late April 1945, Soviet troops captured Berlin. Germany surrendered in May 1945. In the Pacific, American forces advanced toward Japan. In August 1945, the United States dropped atomic bombs on Hiroshima and Nagasaki. The Soviet Union then declared war on Japan. Japan surrendered on 15 August 1945. The surrender documents were signed on 2 September 1945 aboard the USS Missouri, which ended the war.

Aftermath

Main articles: Aftermath of World War II and Consequences of Nazism

After the war, the Allies set up governments to run Austria and Germany for a time. Germany was split into western and eastern occupation zones. In 1949, these became two separate countries, West Germany and East Germany. Austria became a single democratic country again in 1955. A denazification program was started to remove Nazi ideas from society. Some Nazi leaders were put on trial for their crimes at the Nuremberg trials. Germany lost about a quarter of its land. Some of it went to Poland and the Soviet Union, and many Germans were forced to leave those areas. Italy lost its monarchy and its colonies overseas. To help keep world peace, the Allies formed the United Nations in 1945. The five countries that won the war became the permanent members of its Security Council.

Europe was also divided into Western and Soviet spheres of influence. Many countries in eastern and central Europe, including Poland, Hungary, and Czechoslovakia, came under Soviet control. The United States and the Soviet Union then formed rival military groups, NATO and the Warsaw Pact. Their long rivalry, the Cold War, led both sides to build more weapons in an arms race. It also led to several proxy wars. In Asia, the United States led the occupation of Japan, and Korea was divided. This later led to the Korean War. In China, the civil war started again, and communist forces founded the People's Republic of China. The world economy was badly harmed, but the United States became much richer. The Bretton Woods Conference created the International Monetary Fund to help guide the economy after the war. The US Marshall Plan helped Western Europe recover, and West Germany's fast rebuilding is known as the German economic miracle.

Impact

Main article: Historiography of World War II

Main articles: German-occupied Europe, Resistance during World War II, Collaboration with Nazi Germany and Fascist Italy, Collaboration with the Empire of Japan, and Nazi plunder

Main articles: Military production during World War II and Home front during World War II

Main article: Technology during World War II

Many millions of people died in the war. Most of them were civilians, which means people who were not soldiers. Many people died from hunger, disease and hardship. The Soviet Union had the most deaths, followed by China, Germany and Poland. The Nazis killed many Jews in the Holocaust. They also killed many Slavs and Romani people, and others they wrongly considered inferior. Many civilians were killed in genocides and other deliberate killings. The people responsible were later put on trials following the war and found guilty of crimes against humanity and genocides.

Germany, Japan and the Soviet Union also forced many people to work without choice, using slave labourers and forced labour. Germany took large amounts of money from the lands it controlled. Japan described the countries it controlled as part of the Greater East Asia Co-Prosperity Sphere. The Allies had more people and more factories, and the United States made many of the weapons the Allies used. New technologies also developed during the war, including radar, jet aircraft, aircraft carriers, submarines, and the first programmable computers.