World War II

Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km (over 11 miles) into the air. August 9 , 1945 World War II or the Second World War was a global conflict that began on 7 July 1937 , in Asia and 1 September 1939 , in Europe and lasted until 1945 , involving the majority of the world's countries and every inhabited continent. Virtually all countries that participated in World War I were involved in World War II. It was the most extensive and expensive armed conflict in the history of the World. Attributed in varying degrees to the Treaty of Versailles , the Great Depression , nationalism, and militarism, the causes of the war are a matter of debate. On which date the war began is also debated, cited as either the German invasion of Poland on 1 September 1939 , the Japanese invasion of China on 7 July 1937 (the start of the Second Sino-Japanese War ), or earlier yet the 1931 Japanese invasion of Manchuria . Still others argue that the two world wars are one conflict separated only by a "ceasefire". Fighting occurred across the Atlantic Ocean , in Western and Eastern Europe , in the Mediterranean Sea , Africa , the Middle East , in the Pacific and South East Asia , and it continued in China. In Europe, the war ended with the surrender of Germany on 8 May 1945 ( V-E and Victory Days), but continued in Asia until Japan surrendered on 15 August 1945 ( V-J Day ). Approximately 57 million people died as a result of the war , including acts of genocide such as the Holocaust , the Rape of Nanking , and General Ishii Shiro 's Unit 731 experiments in Pingfan . As a case of total war , it involved the " home front " and bombing of civilians to a new degree. Atomic weapons , jet aircraft , and RADAR are only a few of many war-time inventions . Post-war Europe was partitioned into Western and Soviet spheres of influence , the former undergoing economic reconstruction under the Marshall Plan and the latter becoming satellite states of the Soviet Union. Western Europe largely aligned as NATO , and Eastern Europe largely as the Warsaw pact , alliances which were fundamental to the ensuing Cold War . In Asia, the United States' military occupation of Japan led to its democratization, and China came to split into the Communist People's Republic of China and the Nationalist Republic of China .

It was the most widespread war in history, with more than 100 million military personnel mobilised. In a state of " total war ," the major participants placed their entire economic, industrial, and scientific capabilities at the service of the war effort, erasing the distinction between civilian and military resources. Marked by significant action against civilians, including the Holocaust and the only use of nuclear weapons in warfare , it was the deadliest conflict in human history , and it has been estimated that it resulted in fifty million to over seventy million fatalities . The war is generally accepted to have begun on 1 September 1939, with the invasion of Poland by Nazi Germany and subsequent declarations of war on Germany by France and most of the countries of the British Empire and Commonwealth . China and Japan were already at war by this date, whereas other countries that were not initially involved joined the war later in response to events such as the German invasion of the Soviet Union and the Japanese attacks on the U.S. Pacific Fleet at Pearl Harbor and on British overseas colonies , which triggered declarations of war on Japan by the United States , the British Commonwealth , and the Netherlands . The war ended with the total victory of the Allies over Germany and Japan in 1945. World War II left the political alignment and social structure of the world significantly changed. While the United Nations was established to foster international cooperation and prevent future conflicts, the Soviet Union and the United States emerged as rival superpowers , setting the stage for the Cold War , which lasted for the next forty-six years. Meanwhile, the acceptance of the principle of self-determination accelerated decolonization movements in Asia and Africa, while Western Europe began moving toward economic recovery and increased political integration . "Second World War" is preferred by British authors, "World War II" by American authors; both versions are correct Sommerville, Donald (14 December 2008). The Complete Illustrated History of World War Two: An Authoritative Account of the Deadliest Conflict in Human History with Analysis of Decisive Encounters and Landmark Engagements . China in the anti-Japanese War, 1937–1945: politics, culture and society. "Australia Declares War on Japan" . ibiblio . "The Kingdom of The Netherlands Declares War with Japan" . ibiblio. 2007 .

Participants Allies Axis Commanders and leaders Main Allied leaders Joseph Stalin Franklin Roosevelt Winston Churchill Chiang Kai-shek Main Axis leaders Adolf Hitler Hirohito Benito Mussolini Casualties and losses Military dead: Over 16,000,000 Civilian dead: Over 45,000,000 Total dead: Over 61,000,000 (1937–45) ... further details Military dead: Over 8,000,000 Civilian dead: Over 4,000,000 Total dead: Over 12,000,000 (1937–45) ... further details World War II ( WWII or WW2 ), also known as the Second World War (after the recent Great War ), was a global war that lasted from 1939 to 1945, though related conflicts began earlier. It involved the vast majority of the world's nations —including all of the great powers —eventually forming two opposing military alliances : the Allies and the Axis . It was the most widespread war in history, and directly involved more than 100 million people from over 30 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 (during which approximately 11 million people were killed) and the strategic bombing of industrial and population centres (during which approximately one million people were killed, including the use of two 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 Asia and the Pacific 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 conquered or controlled much of continental Europe, and formed the Axis alliance with Italy and Japan . Following the Molotov–Ribbentrop Pact , Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Poland , Finland , Romania and the Baltic states . The United Kingdom and the British Commonwealth were the only Allied forces continuing the fight against the European Axis powers, with campaigns in North Africa and the Horn of Africa as well as the long-running Battle of the Atlantic . In June 1941, the European Axis powers launched an invasion of the Soviet Union , opening the largest land theatre of war in history , which trapped the major part of the Axis' military forces into a war of attrition . In December 1941, Japan attacked the United States and European territories in the Pacific Ocean, and quickly conquered much of the Western Pacific. The Axis advance halted in 1942 when Japan lost the critical Battle of Midway , near Hawaii , and Germany was defeated in North Africa and then, decisively, at Stalingrad in the Soviet Union. In 1943, with a series of German defeats on the Eastern Front , the Allied invasion of Italy which brought about Italian surrender, and Allied victories in the Pacific, the Axis lost the initiative and undertook strategic retreat on all fronts. In 1944, the Western Allies invaded German-occupied France , while the Soviet Union regained all of its territorial losses and invaded Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in South Central China and Burma , while the Allies crippled 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 and the refusal of Japan to surrender under its terms, 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, the possibility of additional atomic bombings, and the Soviet Union's declaration of war on Japan and invasion of Manchuria , Japan surrendered on 15 August 1945. Thus ended the war in Asia, cementing the total victory of the Allies. World War II altered the political alignment and social structure of the world. The United Nations (UN) was established to foster international co-operation and prevent future conflicts. The victorious great powers —the United States, the Soviet Union, China, the United Kingdom, and France—became 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 waned, 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 end pre-war enmities and to create a common identity. There are <ref group=lower-alpha> tags or templates on this page, but the references will not show without a template or template (see the help page ). The UN Security Council . Nobel Lecture by the European Union .

1939–1945 global conflict "The Second World War", "World War Two", and "WWII" redirect here. Roosevelt Chiang Kai-shek Main Axis leaders : Adolf Hitler Hirohito Benito Mussolini Casualties and losses Military dead: Over 16,000,000 Civilian dead: Over 45,000,000 Total dead: Over 61,000,000 (1937–1945) ... further details Military dead: Over 8,000,000 Civilian dead: Over 4,000,000 Total dead: Over 12,000,000 (1937–1945) ... further details World War II or the Second World War , often abbreviated as WWII or WW2 , was a global conflict that lasted from 1939 to 1945. The vast majority of the world's countries , including all of the great powers , fought as part of two opposing military alliances : the Allies and the Axis . Many participants threw their economic, industrial, and scientific capabilities behind this total war , blurring the distinction between civilian and military resources. Aircraft played a major role , enabling the strategic bombing of population centres and the delivery of the only two nuclear weapons ever used in war. World War II was by far the deadliest conflict in history, resulting in an estimated 70 to 85 million fatalities , mostly among civilians. Tens of millions died due to genocides (including the Holocaust ), starvation , massacres , and disease . In the wake of Axis defeat, Germany , Austria and Japan were occupied , and war crimes tribunals were conducted against German and Japanese leaders . The causes of World War II are debated, but contributing factors included the Second Italo-Ethiopian War , Spanish Civil War , Second Sino-Japanese War , Soviet–Japanese border conflicts , the rise of fascism in Europe , and European tensions in the aftermath of World War I . World War II is generally considered to have begun on 1 September 1939, when Nazi Germany , under Adolf Hitler , invaded Poland . The United Kingdom and France subsequently declared war on Germany on 3 September. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union had partitioned Poland and marked out their " spheres of influence " across Finland , Estonia, Latvia, Lithuania and Romania . From late 1939 to early 1941, in a series of campaigns and treaties , Germany conquered or controlled much of continental Europe , in a military alliance with Italy , Japan and other countries called the Axis. Following the onset of campaigns in North Africa and East Africa , and the fall of France in mid-1940, the war continued primarily between the European Axis powers and the British Empire , with war in the Balkans , the aerial Battle of Britain , the Blitz of the United Kingdom, and the Battle of the Atlantic . On 22 June 1941, Germany led the European Axis powers in an invasion of the Soviet Union , opening the Eastern Front , the largest land theatre of war in history. Japan, which aimed to dominate Asia and the Pacific , was at war with the Republic of China by 1937. In December 1941, Japan attacked American and British territories with near-simultaneous offensives against Southeast Asia and the Central Pacific , including an attack on the U.S. fleet at Pearl Harbor which resulted in the United States and United Kingdom declaring war against Japan. The European Axis powers declared war on the United States in solidarity. Japan soon conquered much of the western Pacific, but its advances were halted in 1942 after losing the critical Battle of Midway ; later, Germany and Italy were defeated in North Africa and at Stalingrad in the Soviet Union. Key setbacks in 1943—including a series of German defeats on the Eastern Front, the Allied invasions of Sicily and the Italian mainland , and Allied offensives in the Pacific—cost the Axis powers their initiative and forced them into strategic retreat on all fronts. In 1944, the Western Allies invaded German-occupied France , while the Soviet Union regained its territorial losses and pushed Germany and its allies back. During 1944 and 1945, Japan suffered reversals in mainland Asia, while the Allies crippled the Japanese Navy and captured key western Pacific islands. The war in Europe concluded with the liberation of German-occupied territories and the invasion of Germany by the Western Allies and the Soviet Union, culminating in the Fall of Berlin to Soviet troops, Hitler's suicide , and the German unconditional surrender on 8 May 1945 . Following the refusal of Japan to surrender on the terms of the Potsdam Declaration (issued 26 July 1945), the United States dropped the first atomic bombs on the Japanese cities of Hiroshima on 6 August and Nagasaki on 9 August. Faced with an imminent invasion of the Japanese archipelago , the possibility of additional atomic bombings, and the Soviet Union's declared entry into the war against Japan on the eve of invading Manchuria , Japan announced on 10 August its intention to surrender, signing a surrender document on 2 September 1945 . World War II changed the political alignment and social structure of the globe and set the foundation for the international order of the world's nations for the rest of the 20th century and into the present day. The United Nations was established to foster international co-operation and prevent future conflicts, with the victorious great powers—China, France, the Soviet Union, the United Kingdom, and the United States—becoming the permanent members of its Security Council . The Soviet Union and the United States emerged as rival superpowers , setting the stage for the nearly half-century-long Cold War . In the wake of European devastation, the influence of its great powers waned, triggering the decolonisation of Africa and Asia . Most countries whose industries had been damaged moved towards economic recovery and expansion . Political and economic integration, especially in Europe , began as an effort to forestall future hostilities, end pre-war enmities, and forge a sense of common identity. There are <ref group=lower-alpha> tags or templates on this page, but the references will not show without a template or template (see the help page ).

Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war . Tanks and aircraft played major roles , enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people , more than half of whom were civilians. Millions died in genocides , including the Holocaust , and by massacres, starvation, and disease. After the Allied victory, Germany , Austria , Japan , and Korea were occupied, and German and Japanese leaders were tried for war crimes . The causes of World War II included unresolved tensions in the aftermath of World War I and the rise of fascism in Europe and militarism in Japan . Key events preceding the war included Japan's invasion of Manchuria in 1931, the Spanish Civil War , the outbreak of the Second Sino-Japanese War in 1937, and Germany's annexations of Austria and the Sudetenland . World War II is generally considered to have begun on 1 September 1939, when Nazi Germany , under Adolf Hitler , invaded Poland , after which the United Kingdom and France declared war on Germany. Poland was divided between Germany and the Soviet Union under the Molotov–Ribbentrop Pact . In 1940, the Soviet Union annexed the Baltic states and parts of Finland and Romania . After the fall of France in June 1940, the war continued mainly between Germany and the British Empire , with fighting in the Balkans , Mediterranean, and Middle East , the aerial Battle of Britain and the Blitz , and the naval Battle of the Atlantic . Through campaigns and treaties, Germany gained control of much of continental Europe and formed the Axis alliance with Italy , Japan , and other countries. In June 1941, Germany invaded the Soviet Union , opening the Eastern Front and initially making large territorial gains. In December 1941, Japan attacked American and British territories in Asia and the Pacific , including at Pearl Harbor in Hawaii , leading the United States to enter the war against Japan and Germany. Japan conquered much of coastal China and Southeast Asia, but its advances in the Pacific were halted in June 1942 at the Battle of Midway . In early 1943, Axis forces were defeated in North Africa and at Stalingrad in the Soviet Union, and that year their continued defeats on the Eastern Front, an Allied invasion of Italy , and Allied offensives in the Pacific forced them into retreat on all fronts. In 1944, the Western Allies invaded France at Normandy as the Soviet Union recaptured its pre-war territory and the US crippled Japan's navy and captured key Pacific islands . The war in Europe concluded with the liberation of German-occupied territories ; invasions of Germany by the Western Allies and the Soviet Union, which culminated in the fall of Berlin to Soviet troops; and Germany's unconditional surrender on 8 May 1945 . On 6 and 9 August, the US dropped atomic bombs on Hiroshima and Nagasaki in Japan. Faced with an imminent Allied invasion , the prospect of further atomic bombings, and a Soviet declaration of war and invasion of Manchuria , Japan announced its unconditional surrender on 15 August, and signed a surrender document on 2 September 1945 . World War II transformed the political, economic, and social structures of the world, and established the foundation of international relations for the rest of the 20th century and into the 21st century. The United Nations was created to foster international cooperation and prevent future conflicts, with the victorious great powers—China, France, the Soviet Union, the UK, and the US—becoming the permanent members of its security council . The Soviet Union and the US emerged as rival superpowers , setting the stage for the half-century Cold War . In the wake of Europe's devastation, the influence of its great powers waned, triggering the decolonisation of Africa and of Asia . Many countries whose industries had been damaged moved towards economic recovery and expansion . There are <ref group=lower-alpha> tags or templates on this page, but the references will not show without a template or template (see the help page ).