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World War II
By: History.com Editors
Updated: June 27, 2023 | Original: October 29, 2009
World War II, the largest and deadliest conflict in human history, involved more than 50 nations and was fought on land, sea and air in nearly every part of the world. Also known as the Second World War, it was caused in part by the economic crisis of the Great Depression and by political tensions left unresolved following the end of World War I.
The war began when Nazi Germany invaded Poland in 1939 and raged across the globe until 1945, when Japan surrendered to the United States after atomic bombs were dropped on Hiroshima and Nagasaki. By the end of World War II, an estimated 60 to 80 million people had died, including up to 55 million civilians, and numerous cities in Europe and Asia were reduced to rubble.
Among the people killed were 6 million Jews murdered in Nazi concentration camps as part of Hitler’s diabolical “Final Solution,” now known as the Holocaust. The legacy of the war included the creation of the United Nations as a peacekeeping force and geopolitical rivalries that resulted in the Cold War.
Leading up to World War II
The devastation of the Great War (as World War I was known at the time) had greatly destabilized Europe, and in many respects World War II grew out of issues left unresolved by that earlier conflict. In particular, political and economic instability in Germany, and lingering resentment over the harsh terms imposed by the Versailles Treaty, fueled the rise to power of Adolf Hitler and National Socialist German Workers’ Party, abbreviated as NSDAP in German and the Nazi Party in English..
Did you know? As early as 1923, in his memoir and propaganda tract "Mein Kampf" (My Struggle), Adolf Hitler had predicted a general European war that would result in "the extermination of the Jewish race in Germany."
After becoming Chancellor of Germany in 1933, Hitler swiftly consolidated power, anointing himself Führer (supreme leader) in 1934. Obsessed with the idea of the superiority of the “pure” German race, which he called “Aryan,” Hitler believed that war was the only way to gain the necessary “Lebensraum,” or living space, for the German race to expand. In the mid-1930s, he secretly began the rearmament of Germany, a violation of the Versailles Treaty. After signing alliances with Italy and Japan against the Soviet Union , Hitler sent troops to occupy Austria in 1938 and the following year annexed Czechoslovakia. Hitler’s open aggression went unchecked, as the United States and Soviet Union were concentrated on internal politics at the time, and neither France nor Britain (the two other nations most devastated by the Great War) were eager for confrontation.
Outbreak of World War II (1939)
In late August 1939, Hitler and Soviet leader Joseph Stalin signed the German-Soviet Nonaggression Pact , which incited a frenzy of worry in London and Paris. Hitler had long planned an invasion of Poland, a nation to which Great Britain and France had guaranteed military support if it were attacked by Germany. The pact with Stalin meant that Hitler would not face a war on two fronts once he invaded Poland, and would have Soviet assistance in conquering and dividing the nation itself. On September 1, 1939, Hitler invaded Poland from the west; two days later, France and Britain declared war on Germany, beginning World War II.
On September 17, Soviet troops invaded Poland from the east. Under attack from both sides, Poland fell quickly, and by early 1940 Germany and the Soviet Union had divided control over the nation, according to a secret protocol appended to the Nonaggression Pact. Stalin’s forces then moved to occupy the Baltic States (Estonia, Latvia and Lithuania) and defeated a resistant Finland in the Russo-Finnish War. During the six months following the invasion of Poland, the lack of action on the part of Germany and the Allies in the west led to talk in the news media of a “phony war.” At sea, however, the British and German navies faced off in heated battle, and lethal German U-boat submarines struck at merchant shipping bound for Britain, sinking more than 100 vessels in the first four months of World War II.
World War II in the West (1940-41)
On April 9, 1940, Germany simultaneously invaded Norway and occupied Denmark, and the war began in earnest. On May 10, German forces swept through Belgium and the Netherlands in what became known as “blitzkrieg,” or lightning war. Three days later, Hitler’s troops crossed the Meuse River and struck French forces at Sedan, located at the northern end of the Maginot Line , an elaborate chain of fortifications constructed after World War I and considered an impenetrable defensive barrier. In fact, the Germans broke through the line with their tanks and planes and continued to the rear, rendering it useless. The British Expeditionary Force (BEF) was evacuated by sea from Dunkirk in late May, while in the south French forces mounted a doomed resistance. With France on the verge of collapse, Italy’s fascist dictator Benito Mussolini formed an alliance with Hitler, the Pact of Steel, and Italy declared war against France and Britain on June 10.
On June 14, German forces entered Paris; a new government formed by Marshal Philippe Petain (France’s hero of World War I) requested an armistice two nights later. France was subsequently divided into two zones, one under German military occupation and the other under Petain’s government, installed at Vichy France. Hitler now turned his attention to Britain, which had the defensive advantage of being separated from the Continent by the English Channel.
To pave the way for an amphibious invasion (dubbed Operation Sea Lion), German planes bombed Britain extensively beginning in September 1940 until May 1941, known as the Blitz , including night raids on London and other industrial centers that caused heavy civilian casualties and damage. The Royal Air Force (RAF) eventually defeated the Luftwaffe (German Air Force) in the Battle of Britain , and Hitler postponed his plans to invade. With Britain’s defensive resources pushed to the limit, Prime Minister Winston Churchill began receiving crucial aid from the U.S. under the Lend-Lease Act , passed by Congress in early 1941.
Hitler vs. Stalin: Operation Barbarossa (1941-42)
By early 1941, Hungary, Romania and Bulgaria had joined the Axis, and German troops overran Yugoslavia and Greece that April. Hitler’s conquest of the Balkans was a precursor for his real objective: an invasion of the Soviet Union, whose vast territory would give the German master race the “Lebensraum” it needed. The other half of Hitler’s strategy was the extermination of the Jews from throughout German-occupied Europe. Plans for the “Final Solution” were introduced around the time of the Soviet offensive, and over the next three years more than 4 million Jews would perish in the death camps established in occupied Poland.
On June 22, 1941, Hitler ordered the invasion of the Soviet Union, codenamed Operation Barbarossa . Though Soviet tanks and aircraft greatly outnumbered the Germans’, Russian aviation technology was largely obsolete, and the impact of the surprise invasion helped Germans get within 200 miles of Moscow by mid-July. Arguments between Hitler and his commanders delayed the next German advance until October, when it was stalled by a Soviet counteroffensive and the onset of harsh winter weather.
World War II in the Pacific (1941-43)
With Britain facing Germany in Europe, the United States was the only nation capable of combating Japanese aggression, which by late 1941 included an expansion of its ongoing war with China and the seizure of European colonial holdings in the Far East. On December 7, 1941, 360 Japanese aircraft attacked the major U.S. naval base at Pearl Harbor in Hawaii , taking the Americans completely by surprise and claiming the lives of more than 2,300 troops. The attack on Pearl Harbor served to unify American public opinion in favor of entering World War II, and on December 8 Congress declared war on Japan with only one dissenting vote. Germany and the other Axis Powers promptly declared war on the United States.
After a long string of Japanese victories, the U.S. Pacific Fleet won the Battle of Midway in June 1942, which proved to be a turning point in the war. On Guadalcanal, one of the southern Solomon Islands, the Allies also had success against Japanese forces in a series of battles from August 1942 to February 1943, helping turn the tide further in the Pacific. In mid-1943, Allied naval forces began an aggressive counterattack against Japan, involving a series of amphibious assaults on key Japanese-held islands in the Pacific. This “island-hopping” strategy proved successful, and Allied forces moved closer to their ultimate goal of invading the mainland Japan.
Toward Allied Victory in World War II (1943-45)
In North Africa , British and American forces had defeated the Italians and Germans by 1943. An Allied invasion of Sicily and Italy followed, and Mussolini’s government fell in July 1943, though Allied fighting against the Germans in Italy would continue until 1945.
On the Eastern Front, a Soviet counteroffensive launched in November 1942 ended the bloody Battle of Stalingrad , which had seen some of the fiercest combat of World War II. The approach of winter, along with dwindling food and medical supplies, spelled the end for German troops there, and the last of them surrendered on January 31, 1943.
On June 6, 1944–celebrated as “D-Day” –the Allies began a massive invasion of Europe, landing 156,000 British, Canadian and American soldiers on the beaches of Normandy, France. In response, Hitler poured all the remaining strength of his army into Western Europe, ensuring Germany’s defeat in the east. Soviet troops soon advanced into Poland, Czechoslovakia, Hungary and Romania, while Hitler gathered his forces to drive the Americans and British back from Germany in the Battle of the Bulge (December 1944-January 1945), the last major German offensive of the war.
An intensive aerial bombardment in February 1945 preceded the Allied land invasion of Germany, and by the time Germany formally surrendered on May 8, Soviet forces had occupied much of the country. Hitler was already dead, having died by suicide on April 30 in his Berlin bunker.
World War II Ends (1945)
At the Potsdam Conference of July-August 1945, U.S. President Harry S. Truman (who had taken office after Roosevelt’s death in April), Churchill and Stalin discussed the ongoing war with Japan as well as the peace settlement with Germany. Post-war Germany would be divided into four occupation zones, to be controlled by the Soviet Union, Britain, the United States and France. On the divisive matter of Eastern Europe’s future, Churchill and Truman acquiesced to Stalin, as they needed Soviet cooperation in the war against Japan.
Heavy casualties sustained in the campaigns at Iwo Jima (February 1945) and Okinawa (April-June 1945), and fears of the even costlier land invasion of Japan led Truman to authorize the use of a new and devastating weapon. Developed during a top secret operation code-named The Manhattan Project, the atomic bomb was unleashed on the Japanese cities of Hiroshima and Nagasaki in early August. On August 15, the Japanese government issued a statement declaring they would accept the terms of the Potsdam Declaration, and on September 2, U.S. General Douglas MacArthur accepted Japan’s formal surrender aboard the USS Missouri in Tokyo Bay.
African American Servicemen Fight Two Wars
World War II exposed a glaring paradox within the United States Armed Forces. Although more than 1 million African Americans served in the war to defeat Nazism and fascism, they did so in segregated units. The same discriminatory Jim Crow policies that were rampant in American society were reinforced by the U.S. military. Black servicemen rarely saw combat and were largely relegated to labor and supply units that were commanded by white officers.
There were several African American units that proved essential in helping to win World War II, with the Tuskegee Airmen being among the most celebrated. But the Red Ball Express, the truck convoy of mostly Black drivers were responsible for delivering essential goods to General George S. Patton ’s troops on the front lines in France. The all-Black 761st Tank Battalion fought in the Battle of the Bulge, and the 92 Infantry Division, fought in fierce ground battles in Italy. Yet, despite their role in defeating fascism, the fight for equality continued for African American soldiers after the World War II ended. They remained in segregated units and lower-ranking positions, well into the Korean War , a few years after President Truman signed an executive order to desegregate the U.S. military in 1948.
World War II Casualties and Legacy
World War II proved to be the deadliest international conflict in history, taking the lives of 60 to 80 million people, including 6 million Jews who died at the hands of the Nazis during the Holocaust . Civilians made up an estimated 50-55 million deaths from the war, while military comprised 21 to 25 million of those lost during the war. Millions more were injured, and still more lost their homes and property.
The legacy of the war would include the spread of communism from the Soviet Union into eastern Europe as well as its eventual triumph in China, and the global shift in power from Europe to two rival superpowers–the United States and the Soviet Union–that would soon face off against each other in the Cold War .
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World War II
World War II was a conflict between 1939 and 1945 that involved all the world's major countries. It was the most destructive war in history and millions of people were killed. It was fought between the Axis (Germany, Japan, and Italy) and the Allies (Britain, the US, and the Soviet Union among others). It began because the leader of Germany, Adolf Hitler, wanted to expand German territory. His Nazi party wanted to create a state with only certain kinds of people in it. This led to the Holocaust. The Axis was eventually defeated by the Allies.
Take the World War II quiz
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What started World War II? ›
Find out about the events and people that led to the war.
The Allies ›
Britain, the US, and the Soviet Union were called the Allied countries.
Germany, Italy, and Japan were called the Axis countries.
Children in wartime ›
What was life like for a child during World War II?
Battle of Britain ›
British and German air forces fought a fierce battle called the Battle of Britain.
The war caused a shortage of food in many countries.
Pearl Harbor ›
In 1941, Japan launched an attack on the US base at Pearl Harbor that changed the course of the war.
Battlefield medicine ›
The war caused many casualties (people injured or killed). Medicine on the battlefield was important for both military and human reasons.
Cracking codes ›
Messages were encoded to stop the enemy getting information. Cracking those codes was crucial for gaining the upper hand.
The Holocaust ›
The Nazis blamed Jewish people for all Germany’s problems at home and abroad. Eventually they started systematically killing them and other groups of people in a campaign called the Holocaust.
Normandy landings ›
In 1944, the Allies launched a mission to take back Europe from the Axis. They landed on the Normandy coast in France.
The atomic bomb ›
The atomic bomb is the most destructive weapon ever used by humanity. It brought about an end to World War II, but at terrible human cost.
The London blitz ›
London was bombarded by thousands of German bombs between 1940 and 1941. This attack became known as the Blitz.
Propaganda is material used by governments to influence public opinion. Posters and radio broadcasts were used by both sides to cheer their own people up and to attack the enemy.
Women in World War II ›
The role of women changed hugely during World War II. Their work in factories and on the land was a crucial part of the war effort.
War in the Atlantic ›
The Battle of the Atlantic was the fierce war waged between German submarines and Allied fleets.
Dresden bombings ›
The devastating bombing of the German city of Dresden was one of the most controversial acts of World War II.
When the war ended in Europe, huge crowds took to the streets in celebration.
French resistance ›
Resistance fighters were ordinary people who fought back against German occupation.
The United Nations ›
The UN was founded after World War II ended, to maintain peace in the world.
- ‹ Women’s suffrage in America
- Bronze Age ›
10 facts about World War 2
Learn about this hugely important event in british history….
In September 1939, Britain entered into what would become the world’s most devastating war to date. Learn all about the events that changed the lives of millions in our World War 2 facts….
World War 2 facts
1. world war 2 was a battle between two groups of countries.
– the “ Allies ” and the “ Axis “. The major Allied Powers were Britain, France, Russia, China and the United States. The major Axis Powers were Germany, Italy and Japan.
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2. Before World War 2 began, Germany was ruled by a man named Adolf Hitler
Together with the Nazi Party , he wanted Germany to rule Europe. To gain more land and power, on 1 September 1939 German troops invaded Poland. After Hitler refused to stop the invasion, Britain and France declared war on Germany – World War II had begun.
3. During the course of the war, German forces advanced through Europe.
By the summer of 1941 they had invaded France , Belgium , Holland , Luxembourg , Denmark , Norway , Greece , Yugoslavia * and the USSR *.
Did you know that we have a FREE downloadable Second World War primary resource ? Great for teachers, homeschoolers and parents alike!
4. Millions of Germans were imprisoned and killed because they didn’t fit the image of the ‘perfect’ German
Hitler wanted to create what he thought was the “best” and strongest race – and to the Nazi Party, this excluded certain groups, such as Jews , Gypsies and those with physical and mental disabilities . In an attempt to eliminate a “racial enemy” outside of Germany, such groups were also persecuted in the countries invaded by German forces.
5. The group most heavily targeted by the Nazis were the Jews
Around six million Jewish people were killed during World War 2 in one of history’s most terrible events – the Holocaust. Racist in his views, Hitler blamed Jewish people for Germany losing World War I and claimed they were dangerous to German people and society.
6. Around the same time that Germany fought for power in Europe, Japan wanted to control Asia and the Pacific
In 1937 (before World War 2 had officially begun) under Emperor Hirohito , Japan attacked China, bringing the two nations into years of conflict.
7. The US didn’t join the war until 1941, when Japan attacked the United States
– at their Naval Base at Pearl Harbor in Hawaii . On 8 December 1941 (the very next day), the US declared War on Japan and, in turn, its German allies.
8. Some countries remained ‘neutral’ in World War 2
Such countries were Spain , Sweden and Switzerland – who chose not to join either side.
9. The Germans surrendered on 8 May 1945
In 1944, an Allied army crossed from Britain to free France from Nazi rule. One year later, Allied armies invaded Germany, forcing the Germans to surrender. After nuclear attacks on Japan’s major cities Hiroshima and Nagasaki , Japan also surrendered to Allied forces in August the same year. World War 2 had ended.
10. Around 64 million people died in World War 2
Find out more about the countries involved in World War 2 with our Germany , Japan and USA facts . Plus, learn about the life of Anne Frank , a young German girl who wrote a world-famous diary…
With thanks to Dr. Matthew Thomas from the National Army Museum and Ian Kikuchi from the Imperial War Museum , London.
*yugoslavia was a country established in 1918 in south-east europe, which included modern-day serbia, montenegro, croatia, slovenia and bosnia-herzegovina., *ussr (union of soviet socialist republics, or the soviet union) was a former country which included modern-day russia, ukraine and estonia, as well as other socialist states., what did you think of our world war 2 facts let us know by leaving a comment below., leave a comment.
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It was a transcendental event for humanity that we must avoid repeating because today there is greater military power and with several countries that have nuclear bombs. It would be a universal disaster without losers and winners.
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3/ & in Africa they invaded Egypt, Tunisia, Sudan, British Somaliland; & and Britain in the Channel Islands; 6/ & Italy wanted to control large tracts of Africa to include Tunisia, Egypt, Sudan, Djibouti & British Somaliland. 8/ Portugal was neutral and so was Eire: if the former held sympathies for Britain the latter was a non belligérant sympathiser of Nazi Germany to the extent of mourning Hitler’s death, generously welcoming German children after the War Marshall Plan funds asssisting the war weary countries, and responding to an invitation to join NATO with a “....only if you give back our six counties”. Who needs enemies with friends like that ?
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my great-grandmother fought in WW2 aged only 15, and survived ! :)
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i have some newspaper clippings from then they are very interesting
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my Grandpa Percy was in the wold war 2
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World War 2 was a terrible and historic event of our planet.
I think it could be better with what the people did when they were at home and what was the daily routine
i have no idea wht I am
man this people didnt know the war was going on and they where working tss
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war war why does it has to be war
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I am writing a story about World War Two and needed some facts, this was very helpful, thankyou! :D
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I need 200 facts for my game board in 1 day my eyes hurt its homework
......in Britans darkest hour :blitz ,V
this helps me a lot
64 million! whoa thats a lot of numbers.
This really Helped me!!!! thx
I wish that it was 20 facts but hey thanks ngk
It helps me
Oh my goodness, National Geographic, you helped with my topic and homework once more. This article gives me so much information and tells me specificly what World War Two is all about.
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go on Britain
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why would Hitler take all of those innocent lives? I dont think he was kind at all!
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