World War II, also known as the Second World War, was a global war. It is generally considered to have
lasted from 1939 to 1945, although some conflicts in Asia that are commonly viewed as becoming part of
the world war had begun earlier than 1939. It involved the vast majority of the world's nationsincluding all of
the great powerseventually forming two opposing military alliances: the Allies and the Axis. It was the most
widespread war in history, with more than 100 million people, from more than 30 different countries. In a
state of "total war", the major participants threw their entire economic, industrial, and scientific capabilities
behind the war effort, erasing the distinction between civilian and military resources. Marked by mass
deaths of civilians, including the Holocaust and the first use of nuclear weapons in combat, it resulted in an
estimated 50 million to 85 million fatalities. These made World War II the deadliest conflict in human history.
The Empire of Japan aimed to dominate East Asia and was already at war with the Republic of China in
1937, but the world war is generally said to have begun on 1 September 1939 with the invasion of Poland by
Germany and subsequent declarations of war on Germany by France and the United Kingdom. From late
1939 to early 1941, in a series of campaigns and treaties, Germany formed the Axis alliance with Italy,
conquering or subduing much of continental Europe. Following the MolotovRibbentrop Pact, Germany and
the Soviet Union partitioned and annexed territories between themselves of their European neighbours,
including Poland, Finland and the Baltic states. The United Kingdom and the other members of the British
Commonwealth were the only major Allied forces continuing the fight against the Axis, with battles taking
place in North Africa as well as the longrunning Battle of the Atlantic. In June 1941, the European Axis
launched an invasion of the Soviet Union, giving a start to the largest land theatre of war in history, which
tied down the major part of the Axis' military forces for the rest of the war. In December 1941, Japan joined
the Axis, attacked the United States and European territories in the Pacific Ocean, and quickly conquered
much of the Western Pacific.
The Axis advance was stopped in 1942. Japan lost a critical battle at Midway, near Hawaii, and never
regained its earlier momentum. Germany was defeated in North Africa and, decisively, at Stalingrad in
Russia. In 1943, with a series of German defeats in Eastern Europe, the Allied invasion of Italy which
brought about that nation's surrender, and American victories in the Pacific, the Axis lost the initiative and
undertook strategic retreat on all fronts. In 1944, the Western Allies invaded France, while the Soviet Union
regained all of its territorial losses and invaded Germany and its allies. During 1944 and 1945 the United
States defeated the Japanese Navy and captured key Western Pacific islands.
The war in Europe ended with an invasion of Germany by the Western Allies and the Soviet Union
culminating in the capture of Berlin by Soviet and Polish troops and the subsequent German unconditional
surrender on 8 May 1945. Following the Potsdam Declaration by the Allies on 26 July 1945, the United
States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki on 6 August and 9 August
respectively. With an invasion of the Japanese archipelago imminent, and the Soviet Union having
declared war on Japan by invading Manchuria, Japan surrendered on 15 August 1945, ending the war in
Asia and cementing the total victory of the Allies over the Axis.
World War II altered the political alignment and social structure of the world. The United Nations was
established to foster international cooperation and prevent future conflicts. The great powers that were the
victors of the warthe United States, the Soviet Union, China, the United Kingdom, and Francebecame the
permanent members of the United Nations Security Council. The Soviet Union and the United States
emerged as rival superpowers, setting the stage for the Cold War, which lasted for the next 46 years.
Meanwhile, the influence of European great powers started to decline, while the decolonisation of Asia and
Africa began. Most countries whose industries had been damaged moved towards economic recovery. Political integration, especially in Europe, emerged as an effort to stabilise postwar relations and cooperate
more effectively in the Cold War.
The start of the war is generally held to be 1 September 1939, beginning with the German invasion of
Poland; Britain and France declared war on Germany two days later. Other dates for the beginning of war
include the start of the Second SinoJapanese War on 7 July 1937.
Others follow the British historian A. J. P. Taylor, who held that the SinoJapanese War and war in Europe
and its colonies occurred simultaneously and the two wars merged in 1941. This article uses the
conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of
Abyssinia on 3 October 1935. The British historian Antony Beevor views the beginning of the Second World
War as the Battles of Khalkhin Gol fought between Japan and the Mongolia, Soviet Union from May to
The exact date of the war's end is also not universally agreed upon. It has been suggested that the war
ended at the armistice of 14 August 1945, rather than the formal surrender of Japan ; in some European
histories, it ended on VE Day . However, the Treaty of Peace with Japan was not signed until 1951, and that
with Germany not until 1990.
World War I had radically altered the political map, with the defeat of the Central Powersincluding Austria
Hungary, Germany and the Ottoman Empireand the 1917 Bolshevik seizure of power in Russia. Meanwhile,
existing victorious Allies such as France, Belgium, Italy, Greece and Romania gained territories, while new
states were created out of the collapse of AustriaHungary and the Russian and Ottoman Empires.
Despite the pacifist movement in the aftermath of the war, the losses still caused irredentist and revanchist
nationalism to become important in a number of European states. Irredentism and revanchism were strong
in Germany because of the significant territorial, colonial, and financial losses incurred by the Treaty of
Versailles. Under the treaty, Germany lost around 13 percent of its home territory and all of its overseas
colonies, while German annexation of other states was prohibited, reparations were imposed, and limits
were placed on the size and capability of the country's armed forces. Meanwhile, the Russian Civil War had
led to the creation of the Soviet Union.
The German Empire was dissolved in the German Revolution of 19181919, and a democratic government,
later known as the Weimar Republic, was created. The interwar period saw strife between supporters of the
new republic and hardline opponents on both the right and left. Although Italy as an Entente ally made
some territorial gains, Italian nationalists were angered that the promises made by Britain and France to
secure Italian entrance into the war were not fulfilled with the peace settlement. From 1922 to 1925, the
Fascist movement led by Benito Mussolini seized power in Italy with a nationalist, totalitarian, and class
collaborationist agenda that abolished representative democracy, repressed socialist, leftwing and liberal
forces, and pursued an aggressive foreign policy aimed at forcefully forging Italy as a world power,
promising the creation of a "New Roman Empire".
In Germany, the Weimar Republic's legitimacy was challenged by rightwing elements such the Freikorps
and the Nazi party, resulting in events such as the Kapp Putsch and the Beer Hall Putsch. With the onset of
the Great Depression in 1929, domestic support for Nazism and its leader Adolf Hitler rose and, in 1933, he
was appointed Chancellor of Germany. In the aftermath of the Reichstag fire, Hitler created a totalitarian
singleparty state led by the Nazis.
The Kuomintang party in China launched a unification campaign against regional warlords and nominally unified China in the mid1920s, but was soon embroiled in a civil war against its former Chinese communist
allies. In 1931, an increasingly militaristic Japanese Empire, which had long sought influence in China as
the first step of what its government saw as the country's right to rule Asia, used the Mukden Incident as a
pretext to launch an invasion of Manchuria and establish the puppet state of Manchukuo.
Too weak to resist Japan, China appealed to the League of Nations for help. Japan withdrew from the
League of Nations after being condemned for its incursion into Manchuria. The two nations then fought
several battles, in Shanghai, Rehe and Hebei, until the Tanggu Truce was signed in 1933. Thereafter,
Chinese volunteer forces continued the resistance to Japanese aggression in Manchuria, and Chahar and
Adolf Hitler, after an unsuccessful attempt to overthrow the German government in 1923, became the
Chancellor of Germany in 1933. He abolished democracy, espousing a radical, racially motivated revision of
the world order, and soon began a massive rearmament campaign. It was at this time that multiple political
scientists began to predict that a second Great War might take place. Meanwhile, France, to secure its
alliance, allowed Italy a free hand in Ethiopia, which Italy desired as a colonial possession. The situation
was aggravated in early 1935 when the Territory of the Saar Basin was legally reunited with Germany and
Hitler repudiated the Treaty of Versailles, accelerated his rearmament programme and introduced
Hoping to contain Germany, the United Kingdom, France and Italy formed the Stresa Front; however, in
June 1935, the United Kingdom made an independent naval agreement with Germany, easing prior
restrictions. The Soviet Union, concerned due to Germany's goals of capturing vast areas of eastern
Europe, wrote a treaty of mutual assistance with France. Before taking effect though, the FrancoSoviet
pact was required to go through the bureaucracy of the League of Nations, which rendered it essentially
toothless. The United States, concerned with events in Europe and Asia, passed the Neutrality Act in
August. In October, Italy invaded Ethiopia, and Germany was the only major European nation to support the
invasion. Italy subsequently dropped its objections to Germany's goal of absorbing Austria.
Hitler defied the Versailles and Locarno treaties by remilitarising the Rhineland in March 1936. He received
little response from other European powers. When the Spanish Civil War broke out in July, Hitler and
Mussolini supported the fascist and authoritarian Nationalist forces in their civil war against the Soviet
supported Spanish Republic. Both sides used the conflict to test new weapons and methods of warfare,
with the Nationalists winning the war in early 1939. In October 1936, Germany and Italy formed the Rome
Berlin Axis. A month later, Germany and Japan signed the AntiComintern Pact, which Italy would join in the
following year. In China, after the Xi'an Incident the Kuomintang and communist forces agreed on a
ceasefire in order to present a united front to oppose Japan.
Italian invasion of Ethiopia
The Second ItaloAbyssinian War was a brief colonial war that began in October 1935 and ended in May
1936. The war was fought between the armed forces of the Kingdom of Italy and the armed forces of the
Ethiopian Empire . The war resulted in the military occupation of Ethiopia and its annexation into the newly
created colony of Italian East Africa ; in addition, it exposed the weakness of the League of Nations as a
force to preserve peace. Both Italy and Ethiopia were member nations, but the League did nothing when
the former clearly violated the League's own Article X.
Spanish Civil War
During the Spanish Civil War, Hitler and Mussolini lent military support to the Nationalist rebels, led by General Francisco Franco. The Soviet Union supported the existing government, the Spanish Republic.
Over 30,000 foreign volunteers, known as the International Brigades, also fought against the Nationalists.
Both Germany and the USSR used this proxy war as an opportunity to test in combat their most advanced
weapons and tactics. The bombing of Guernica by the German Condor Legion in April 1937 heightened
widespread concerns that the next major war would include extensive terror bombing attacks on civilians.
The Nationalists won the civil war in April 1939; Franco, now dictator, bargained with both sides during the
Second World War, but never concluded any major agreements. He did send volunteers to fight on the
eastern front under German command but Spain remained neutral and did not allow either side to use its
Japanese invasion of China
In July 1937, Japan captured the former Chinese imperial capital of Beijing after instigating the Marco Polo
Bridge Incident, which culminated in the Japanese campaign to invade all of China. The Soviets quickly
signed a nonaggression pact with China to lend materiel support, effectively ending China's prior co
operation with Germany. Generalissimo Chiang Kaishek deployed his best army to defend Shanghai, but,
after three months of fighting, Shanghai fell. The Japanese continued to push the Chinese forces back,
capturing the capital Nanking in December 1937 and committed the Nanking Massacre.
In March 1938, Nationalist Chinese force got their first major victory at Taierzhuang but then city Xuzhou
was taken by Japanese in May. In June 1938,Chinese forces stalled the Japanese advance by flooding the
Yellow River; this manoeuvre bought time for the Chinese to prepare their defences at Wuhan, but the city
was taken by October. Japanese military victories did not bring about the collapse of Chinese resistance
that Japan had hoped to achieve; instead the Chinese government relocated inland to Chongqing and
continued the war.
Japanese invasion of the Soviet Union and Mongolia
On 29 July 1938, the Japanese invaded territory across the USSR border and were checked at the Battle of
Lake Khasan. Although the battle was a Soviet victory, the Japanese dismissed it as an inconclusive draw,
and on 11 May 1939 decided to move the JapaneseMongolian border up to the Khalkhin Gol River by
force. After initial successes the Japanese assault on Mongolia was checked by the Red Army that inflicted
the first major defeat on the Japanese Kwantung Army.
These clashes convinced some factions in the Japanese government that they should focus on conciliating
the Soviet government to avoid interference in the war against China and instead turn their military attention
southward, towards the US and European holdings in the Pacific, and also prevented the sacking of
experienced Soviet military leaders such as Georgy Zhukov, who would later play a vital role in the defence
European occupations and agreements
In Europe, Germany and Italy were becoming bolder. In March 1938, Germany annexed Austria, again
provoking little response from other European powers. Encouraged, Hitler began pressing German claims
on the Sudetenland, an area of Czechoslovakia with a predominantly ethnic German population; and soon
Britain and France followed the counsel of prime minister Neville Chamberlain and conceded this territory to
Germany in the Munich Agreement, which was made against the wishes of the Czechoslovak government,
in exchange for a promise of no further territorial demands. Soon afterwards, Germany and Italy forced
Czechoslovakia to ced