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The United States and our allies, the United Kingdom, Soviet Union, France, and China beat the Axis Powers of Germany, Italy, and Japan. Wars don’t usually end with one side completely defeating the other and taking control of all of their land, but that’s how World War II ended.

Why did it turn out that way? Was it better ideas, or better equipment? Was it just because the Allies had more people, or because there was almost no fighting in America? Perhaps it was because of leaders, or better inventions.

What do you think? What thing or combination of things led to the final result? Why did the Allies win?


In June 1941, Hitler broke the agreement he made with Stalin and attacked the Soviet Union. The Germans killed both Red Army soldiers and civilians by the millions. Hitler’s surprise attack brought the Soviet Union into the war on the side of the Allies, an unlikely friend, but one that was important. With Germany fighting the Soviets in the East, and the British and Americans in the West, its armies would always be divided.

America, too, was fighting on two fronts and had to make hard choices about how to divide its military power. Roosevelt thought that if Hitler and the Nazis were able to take all of Europe, they would be harder to fight than if Japan took control of all of the Pacific. American scientists worried that, with enough time, German scientists might make a nuclear weapon. So American leaders decided that defeating Hitler was the first priority.

American leaders wanted to be more aggressive about attacking the Germans than the British. Landing on the beach of France would be a way to directly attack Germany, but British leaders were not sure it would work. Winston Churchill was afraid that invading France would cost too many men and supplies would hurt the Allies’ chances of winning. So, Roosevelt and Churchill agreed to start a blockade to stop supplies from getting to Germany and to begin bombing German cities and factories. The army would attack Hitler’s army at their weakest points first and slowly move toward Germany. The plan was known as closing the ring and the first step was to fight the German army in North Africa.

The attack started in October 1942. Led by British General Bernard Montgomery, the British army attacked German and Italian soldiers led by the “Desert Fox,” German Field Marshal Erwin Rommel, at El Alamein in Egypt. As the British forced a German retreat, more British and American soldiers landed on the west coast of Africa. Rommel was smart, but he had fewer soldiers and had to give up in the end. The Allies won their first important victory against Germany in North Africa.

At the same time, the Soviets started winning against the German army at Stalingrad. When spring came in 1943, the Allies had started to close the ring.

After beating the Germans in Northern Africa, the Allies took the next step toward Germany by attacking Italy. American and British leaders believed that when the Italian people did not want to fight and that when the Allies attacked, the Italian people would rise up and get rid of Mussolini. German leaders were afraid that this would give the Allies a free road through Italy to Germany, so German soldiers moved in to defend Italy. Even with the German army in Italy, Mussolini was arrested, and Italy surrendered. Even without the Italians to help them, German soldiers defended Italy, and some of the worst fighting of the war happened in Italy.

Primary Source: Photograph
American bombers over burning German cities. Large attacks by many British and American bombers helped end Germany’s ability to fight the war.


The time had finally come for a full attack against the Germans in Europe. British and American troops had taken back North Africa and pushed into Italy. Soviet troops had turned back the Germans at Stalingrad and were slowly taking back their land.

By 1944, American and British planes from airports in England had started around-the-clock bombing attacks at the factories, railroad lines, ports, and other important places in Germany. Allied leaders wanted to stop Germany from being able to fight war. Firebombing of cities was meant to burn entire neighborhoods. Similar attacks took place on Japanese cities. Before the war ended, 40% of all the homes in major Japanese cities had been burned on purpose by Allied attacks and hundreds of thousands of people died.

Since the start of the war, Hitler’s armies had control of all of France, the Low Countries of Belgium, and the Netherlands, and most of Eastern Europe. His Atlantic Wall of defenses along the beaches of France made any invasion of his territory dangerous. Stalin’s Soviet Union had been the only allied leader fighting Hitler in Europe. Stalin wanted Great Britain and the United States to attack the Germans in France to give his soldiers in the East a break. Finally, in 1944, the Americans and British were ready, and it was going to be the largest invasion force in history.

Primary Source: Photograph
The city of Dresden, Germany after the Americans firebombed it. Attacking civilians on purpose has been criticized after the war.

The Allies spent a lot of time trying to confuse the Germans by making fake messages about their plans. The trick worked and German leaders thought that the attack would come at Calais.  But the truth was that General Dwight Eisenhower planned Operation Overlord for Normandy, a different beach in France.

Just after midnight on June 6, 1944, Allied soldiers parachuted behind enemy lines to cut communications. As the German guards looked out at the English Channel in the morning, they saw the largest group of ships ever in history heading toward the French beaches. There were five points of attack. Gold and Sword Beaches were taken by the British, and Juno Beach was attacked by Canadian soldiers. The Americans had to capture Utah and Omaha Beaches. Many men died on the first day of the attack. Still, by the end of the day, German troops retreated and the Allies had taken control of the beaches. The successful landing in France on June 6, or D-Day, along with the Battle of Stalingrad in the East, are the turning point battles in the war against Hitler’s Germany.

Primary Source: Photograph
Within days of the successful landing on D-Day, thousands of men, tanks, trucks, and supplies were being unloaded in support of the soldiers pushing forward through France.

After D-Day, the German army was defeated little by little. Paris was liberated in August 1944 as the Allies pushed slowly toward the east. At the same time, the Soviet Union was moving into Germany from the east. Trying to put off what was going to be a final defeat, Hitler made one final attack in December 1944. The attack caught the Allies by surprise and the Battle of the Bulge, so named because of the shape of the battle lines on a map, slowed the Allied armies, but it did not stop them.  By the spring of 1945, most of the German armies had been defeated and the Americans, British, and Free French were racing the Soviets to Berlin.

Along the way, they found Hitler’s concentration camps and saw the horrible things the Nazis had done. American soldiers saw humans that looked more like skeletons, gas chambers, crematoriums, and thousands of victims. American leaders knew that Hitler was killing some Jewish people, but they were surprised to find out about the Holocaust of 12 million Jews.

The Soviets got to Berlin first and found that Adolf Hitler had killed himself the day before. The last German soldiers gave up on May 8, 1945, a day now called V-E Day, short for Victory in Europe.


Pearl Harbor was only the beginning of Japanese attacks on the United States. Two days after attacking Pearl Harbor, they took the island of Guam, and two weeks after that they took Wake Island. Before 1941 ended, the Philippines came under attack.

Led by General Douglas MacArthur, the Americans hoped they could hold the Philippines. MacArthur and the Americans tried to hold off the Japanese at an old fort called Corregidor, but in the end, the Japanese were stronger and they had no choice but to surrender the Philippines. Before being called away by President Roosevelt, General MacArthur promised, “I shall return.”

After MacArthur escaped, the Japanese forced Filipino and American prisoners of war to walk to a prison in Bataan. This 85-mile trip, remembered as the Bataan Death March, is an example of how cruel the Japanese military was to prisoners. 16,000 people died along the way, and many more died in prison.

Primary Source: Photograph
The American aircraft carrier USS Yorktown at the moment a torpedo hit during the Battle of Midway. Anti-aircraft shells were exploding above the ship.

In June 1942, Japan wanted to take Midway Island, an American base about 1,000 miles from Hawaii. The Japanese plan, like the earlier attack on Pearl Harbor, was to stop the United States from fighting in the Pacific so that Japan would be free to do what it wanted in Asia. The Japanese thought another defeat would get the United States to give up. This time their plan did not work because the Americans were more powerful than the Japanese thought, and because American cryptographers had broken the Japanese navy’s secret codes and knew what the Japanese were planning.

Primary Source: Photograph
Joe Rosenthal’s famous picture of Marines at the top of Mount Suribachi on Iwo Jima.

Four Japanese and three American aircraft carriers joined in the battle. All four of Japan’s large carriers, part of the six-carrier force that had attacked Pearl Harbor six months earlier, and a heavy cruiser were sunk, while the Americans lost only one carrier and a destroyer. After Midway, Japan could not replace its lost men, ships, and planes fast enough to fight off the Americans. For this reason, Midway is the turning point in the Pacific War. After the Battle of Midway, the Americans slowly moved west across the Pacific, attacking Japanese-held islands on their way to Japan. Instead of attacking the Japanese on every island of Micronesia and Melanesia, the United States chose a path that would move American forces closer and closer to the Japanese mainland by attacking the islands where the Japanese were the weakest and skipping those that would be harder to attack.  This left them cut off from communication and supplies. Using this Island Hopping plan, General MacArthur led the advance toward Japan.

In October 1944, MacArthur kept his promise and returned to the Philippines. In the first half of 1945, Americans took the island of Iwo Jima, which was used as an airport for bombers to attack Japan.

The final island held by Japan was the large island of Okinawa. The attack on Okinawa has been called kotetsu no ame, the “rain of steel” in Japanese because of how terrible the fighting was and because of the Japanese kamikaze suicide airplane attacks. About 160,000 soldiers died on both sides. About 150,000 Okinawan people also died, which was half of all the people on the island.

During the battle, Americans found out that President Roosevelt had died. For many young soldiers, Roosevelt was the only president they could remember. He had been elected four times and served a total of 12 years in office. Vice-President Harry Truman took his place and it fell to the new president to decide how to end war in the Pacific. After seeing how bad the Battle of Okinawa had been, Truman wanted to find a way to end the war without having to attack the four main islands of Japan.


Early in 1939, the world’s scientists discovered that German physicists had learned the secrets of splitting a uranium atom. Fears spread that the Nazi scientists might use that energy to make an atomic bomb.

Scientists Albert Einstein and Enrico Fermi agreed that the president must be told about the dangers of atomic technology in the hands of the Axis powers. Fermi traveled to Washington, but few government leaders listened.

Einstein wrote a letter to President Roosevelt to tell him that America needed to build an atomic bomb before the Germans. Roosevelt thought it was too expensive and wouldn’t be needed, but agreed to start working on it anyway, which was called the Manhattan Project.

In 1942, Fermi led a group of physicists to produce the first controlled nuclear chain reaction at the University of Chicago. After this success, the government spent more money on the project. Nuclear facilities were built at Oak Ridge, Tennessee and Hanford, Washington. The main factory was built at Los Alamos, New Mexico. Robert Oppenheimer was put in charge of putting the pieces together at Los Alamos. In all, $2 billion was spent on making the atomic bomb, and the Manhattan Project gave jobs to over 120,000 Americans.

Keeping the project a secret was very important. Roosevelt and Churchill agreed that Stalin should not know about it, and no one in America ever knew about it, so there was never a debate about if building an atomic bomb was a good idea or not. Keeping 120,000 people quiet would have been impossible. Therefore, only a small number of scientists and leaders knew about the final goal. In fact, Vice-President Truman had never heard of the Manhattan Project until he became president.

By the summer of 1945, Oppenheimer was ready to test the first bomb. On July 16, 1945, at Trinity Site in New Mexico, scientists of the Manhattan Project got ready to watch the world’s first atomic bomb.  A bright flash lit up the morning sky and a mushroom cloud reached 40,000 feet.  When the cloud returned to earth it created a half-mile wide crater that turned sand into glass. The explosion blew out windows in homes 100 miles away. Soon word reached President Truman that the bomb had worked. The world had entered the nuclear age.


When Harry Truman learned about the Manhattan Project, he knew he had an important decision to make. He could use the atomic bomb to end the war, but it would mean using the most terrible weapon ever invented.

Americans were tired from four years of war, and it did not seem like Japan was going to give up. Americans had taken Okinawa and Iwo Jima and were firebombing Japanese cities. But Japan still had an army of 2 million men getting ready to fight back against an invasion.

Before using the bomb, the Allies asked the Japanese leaders to give up and warned that if they did not, there would be total destruction, but did not tell them about the new atomic bomb. The Japanese military leaders refused to surrender.

Primary Source: Photograph
A photograph of downtown Hiroshima after the bombing. Everything that was not built of stone or concrete had been destroyed.

On August 6, 1945, a plane called the Enola Gay dropped an atomic bomb on the city of Hiroshima. 70,000 Japanese people died. In the months and years that followed, 100,000 more people died from burns and radiation sicknes

The Japanese leaders still refused to surrender. On August 9, a second atomic bomb was dropped on Nagasaki, where 80,000 Japanese people died.

On August 14, 1945, the Japanese finally gave up. V-J Day, or Victory in Japan Day is remembered on either August 14 or 15, depending on which day it was in the world when people heard the news, or sometimes on September 2, the day the Japanese leaders signed the agreement to surrender on the USS Missouri battleship in Tokyo Bay.


The choice to use the atomic bomb, and to use it on a city in which thousands of civilians would die has been debated.

Some military historians think that Japan was about to give up and America did not need to use the atomic bomb.

Others have said that the choice to use the bomb in Japan and not Germany shows American racism. These people question whether Truman would have been willing to use the bomb against Europeans.

Some said that Truman made a terrible choice that had hurt the United States for many years. Looking into the future, Truman should have seen that using the atomic bomb would lead to other countries wanting atomic bombs of their own.

Some think that the atomic bomb was used to end the war quickly before the Soviets would have a chance to attack Japan from the North. In this view, Truman wanted the United States to be the only country to control Japan, unlike the way Germany had been split up between the Allies.  Other people think that Truman wanted to show the Soviet Union how strong America was. In this way, Hiroshima and Nagasaki may have been the first shots of the Cold War against the Soviets as well as the final shots of World War II.

No matter what the actual reason, the United States is still the only nation in the world to ever use a nuclear bomb in war.

Truman himself said that his choice to drop the bomb was just about winning. An attack like D-Day in Japan would have led to millions of deaths. Truman thought that the bombs saved Japanese lives as well as American lives. He did not want the war to go on any longer.

Some of his critics asked why Truman did not show the bomb’s power by dropping it in the countryside, but the President did not like this idea. He knew that the Japanese might not surrender if the test succeeded, and he thought that if it failed it would be even worse. Even most scientists had not thought about the awful effects of radiation sickness. Truman saw little difference between atomic bombing Hiroshima and firebombing Dresden or Tokyo.

For Truman, war was terrible, winning was the goal, and he saw no reason why he should not use every weapon he could.

The ethical debate over the choice to drop the atomic bomb will probably never end. The bombs did, however, bring an end to the worst war in history and the Manhattan Project that produced it showed how the country could use its resources in a crisis.

However, the use of atomic weapons did start a dangerous arms race as the strongest countries in the world tried to build their own nuclear bombs.  This Cold War with the Soviet Union lasted for the next 50 years.

Secondary Source: Statue
Sadako Sakasi, a high school student who died from radiation poisoning in Hiroshima attempted to fold 1,000 paper cranes in an effort to bring good luck and recover from the cancer that she eventually died from. She and the paper crane have now become symbols of peace and especially of the effort to rid the world of nuclear weapons. This statue stands in Seattle, Washington. Other statues of Sadako have been erected all around the world.


The war ended in Europe when Allied armies turned back Hitler’s attacks in Africa and the Soviet Union and eventually took the city of Berlin. In Asia, the war came to an end before the Americans had to invade Japan itself.

Why was this the way the war ended? What brought about this end, and not some other? Leaders? Technology? More people? Ideals? Plans?

What do you think? Why did the Allies win World War II?



BIG IDEA: Good leadership, economic power, and the use of total war eventually helped the Allies defeat both Germany and Japan. In the end, President Truman’s use of the atomic bomb prevented the need for a full invasion of Japan.

As the war began, Hitler broke his nonaggression pact with Stalin and invaded the Soviet Union. This resulted in an unusual alliance between the communist Soviets and the democracies of the United States, United Kingdom, as well as the Chinese, who had briefly ended their civil war to fight the Japanese.

The Allies concentrated their efforts first in Northern Africa, and after winning there, invaded Italy. The turning points of the war in Europe came on June 4, 1944 (when the British, Americans, free French, and Canadians landed at Normandy on D-Day) and at the Battle of Stalingrad when the Soviets turned back Hitler’s invasion of the Soviet Union.

Intensive bombing campaigns over Germany slowly weakened the enemy as Allied forces pushed inward from both East and West. Eventually Germany collapsed, Hitler committed suicide, and the war in Europe ended.

In the Pacific, the United States suffered humiliating defeats in the early months of the war. After the attack on Pearl Harbor, the Americans were forced to surrender the Philippines to the invading Japanese. The turning point came at the Battle of Midway when the United States was able to sink critical aircraft carriers from the Japanese fleet. Without the resources to rebuild or resupply, the war in the Pacific was a long, slow struggle to recapture tiny islands held by the Japanese. This process resulted in some of the most deadly, but celebrated battles of the Marine Corps’ history.

After retaking the Philippines, the Americans launched an invasion of Okinawa, the last island stronghold before a full invasion of the Japanese mainland would begin. It was one of the most deadly of the entire war. The Japanese used suicide airplane attacks and the Americans devastating the islands with an enormous bombardment.

Meanwhile, Albert Einstein had warned President Roosevelt that Hitler’s scientists might be trying to develop a nuclear bomb and encourage the Americans to create such a weapon first. This top-secret Manhattan Project was a success, and the first atomic bomb was tested in New Mexico.

President Truman took office when Roosevelt died in 1944 and decided to use the atomic bomb to force Japan to surrender. The Americans bombed the Japanese cities of Hiroshima and Nagasaki. There is still debate about the morality of using atomic weapons on cities with large civilian populations. Japan’s surrender in 1945 brought the war to an end. It was the most deadly conflict in human history.



Bernard Montgomery: Top British commander during World War II.

Erwin Rommel: German commander in North Africa during World War II. He was nicknamed the “Desert Fox.”

Dwight Eisenhower: Supreme allied commander in Europe during World War II. He later became president during the 1950s.

Douglas MacArthur: Allied commander in the South Pacific during World War II. He was forced to surrender the Philippines at the start of the war, but led the successful island hopping campaign and eventually accepted the Japanese surrender and was the military governor of occupied Japan.

Harry Truman: American president at the end of World War II. He became president in 1945 when Roosevelt died and made the decision to use the atomic bomb.

Albert Einstein: World famous scientist. His letter to President Roosevelt about the danger of a German nuclear bomb convinced Roosevelt to start the Manhattan Project.

Enrico Fermi: Italian scientist who convinced Einstein to write a letter to President Roosevelt warning him of the danger of nuclear weapons.

Robert Oppenheimer: Scientist who led the Manhattan Project. He is remembered as the Father of the Nuclear Bomb.


Firebombing: Bombing raids using incendiary bombs designed to start fires and burn down large urban areas. The tactic was used extensively by the allies against both German and Japanese cities in World War II.

Island Hopping: MacArthur’s strategy of capturing the less-fortified Japanese islands in the South Pacific and cutting off better defended islands from resupply.

Kamikaze: Suicide attacks by Japanese pilots against American ships.


Einstein’s Letter to Roosevelt: Letter that convinced President Roosevelt to initiate the Manhattan Project and develop a nuclear weapon.


Corregidor: Fortress in the Philippines that was the last holdout for American and Filipino troops against the Japanese invasion in 1942.

Los Alamos, NM: Site of a nuclear research center beginning in World War II.

Trinity Site: Location in a New Mexico desert of the first nuclear explosion in 1945.

Hiroshima: Japanese city that was destroyed in 1945 in the first atomic bomb attack.

Nagasaki: Second Japanese city destroyed by a nuclear bomb in 1945.


North Africa Campaign: Fight between American and British troops led by Eisenhower, and Germans led by Rommel on in North Africa during World War II. The series of battles was notable for its use of tanks.

Battle of Stalingrad: One of the turning point battles of World War II. German forces had attacked deep into the Soviet Union before they were turned back here during the winter of 1942.

Invasion of Italy: Attack by the Allies from North Africa to the island of Sicily and then the Italian Peninsula in 1943.

Operation Overlord: Nickname for the amphibious invasion of France that became D-Day.

D-Day: June 6, 1944. The landing of allied forces at Normandy, France. It was a turning point in the war in Europe.

Battle of the Bulge: Last counterattack by the Germans against the allies along the Western Front in World War II before the total collapse of German defenses.

Holocaust: Hitler’s attempt to murder all Jews in Europe. The genocide resulted in 12 million deaths.

V-E Day: May 8, 1945. The end of World War II in Europe when Germany surrendered.

Bataan Death March: Forced walk of American and Filipino troops from Corregidor to prison camps. 16,000 men died along the way due to Japanese cruelty.

Battle of Midway: Turning point battle in the Pacific in 1942. The Americans d sunk four Japanese aircraft carries. After the battle, the Japanese were unable to rebuild their fleet or train replacement pilots.

Battle of Iwo Jima: 1945 attack by American marines that resulted in one of the most well-known photographs of World War II. The island was used for air raids on Japan.

Battle of Okinawa: Last battle of the Pacific before the planned invasion of the Japanese mainland. The Americans used enormous firepower and Japan began using kamikaze suicide attacks. It was the bloodiest battle of the Pacific War.

V-J Day: The end of World War II when Japan surrendered.


Manhattan Project: Secret project during World War II to develop a nuclear bomb.

Enola Gay: Bomber that dropped the first atomic bomb in 1945.

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