The United States and our allies, the United Kingdom, Soviet Union, France and China defeated the Axis Powers of Germany, Italy and Japan. It was an unusual war in history in that it ended with the unconditional surrender of the enemy and complete occupation of that enemy’s territory.

Why did it turn out that way? Was it better strategy, or better equipment? Was it simply because the Allies had more people, or because there was almost no fighting on American territory? Perhaps it was because of leadership, or technological superiority.

What do you think? What factor or combination of factors led to the ultimate outcome? Why did the Allies win?


In June 1941, Hitler had broken his nonaggression pact with the Soviet Union and marched his armies deep into Soviet territory, where they would kill Red Army regulars 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 proved 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 might. Roosevelt believed that a Nazi-dominated Europe would be far more impregnable that any defenses Japan could build in the Pacific. American scientists worried that, with enough time, German scientists might develop a nuclear weapon. Once Hitler was defeated, the combined Allied forces would concentrate on smashing Japanese ambitions.

American military leaders favored a far more aggressive approach to attacking Germany than their British counterparts. A cross-channel invasion of France from Britain would strike at the heart of Nazi strength, but the British command was dubious. Winston Churchill feared that should such an operation fail, the loss of human life, military resources, and British morale could be fatal. Instead, Roosevelt and Churchill agreed to implement an immediate blockade of supplies to Germany and to begin bombing German cities and munitions centers. The army would attack Hitler’s troops at their weakest points first and slowly advance toward German soil. The plan was known as closing the ring. In December 1941, Roosevelt and Churchill agreed to attack German holdings in North Africa first.

That maneuver was finally executed in October 1942. Nazi troops were occupying much of the African Mediterranean coast, which had been controlled by France prior to the war. Led by British General Bernard Montgomery, British forces struck at German and Italian troops commanded by the “Desert Fox,” German Field Marshal Erwin Rommel, at El Alamein in Egypt. As the British forced a German retreat, Anglo-American forces landed on the west coast of Africa on November 8 to stage a simultaneous assault. Rommel fought gamely, but numbers and positioning soon forced a German surrender. The Allies had achieved their first important joint victory in the North Africa Campaign.

Simultaneously, the Soviets turned the tide against Nazi advances into the Soviet Union by defeating the German forces at Stalingrad. When springtime came in 1943, the Allies had begun to close the ring.

With Northern Africa secured, the Allies took the next step toward Germany by launching invasions of the island of Sicily and Italy. American and British leaders believed that when the Italian people faced occupation of their homeland, they would rise up and overthrow Mussolini. Fearing that the Allies would have a free road up to the border of Austria, German forces began to entrench themselves in Italy. Despite German presence in Italy, Mussolini was arrested and the Italians surrendered to the Allies on September 3. Despite the collapse of Mussolini’s armies, German forces defended the Italian peninsula ferociously, and even when the European war ended in May 1945, the Allies had failed to capture much of Italy.

Primary Source: Photograph

American bombers over burning German cities. Massive raids by fleets of British and American bombers helped end Germany’s ability to wage war.


The time had finally come for a full invasion of Europe. British and American troops had liberated North Africa and pressed into Italy. Soviet troops had turned the tide at Stalingrad and were slowly reclaiming their territory.

By 1944, American and British planes from bases in England had begun around-the-clock bombing missions aimed at the industrial heart of Germany. After initially targeting only factories, railroad lines, ports and other sites that were clearly critical to Germany’s ability to fight, Allied planners widened their attacks and aimed to destroy the entire German will and ability to make war. Firebombing of cities was intended to burn entire neighborhoods. Similar attacks took place on Japanese cities. Before the war ended, 40% of all the housing in major Japanese cities had been destroyed intentionally by Allied air raids and hundreds of thousands of civilians died.

Since the outbreak of war, Stalin had been the only allied leader fighting Hitler on the mainland. Hitler’s armies maintained 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 coastlines of France made any invasion of his territory treacherous. Stalin was demanding an all-out effort to liberate France from German occupation to help relieve the pressure his forces were facing in the East. Now, an invasion force greater than any in the history of the world was amassing in southern Britain toward that end.

Primary Source: Photograph

The ruins of Dresden, Germany after the Americans firebombed the city. Intentional targeting of civilians by Allied commanders has been criticized after the war.

A great game of espionage unfolded. If the Germans could discover when and where the attack would occur, they could concentrate all their efforts in one area, and the invasion would be doomed. The Allies staged phony exercises meant to confuse German intelligence. Two-dimensional dummy tanks were arranged to distract air surveillance. German commanders had good reason to believe the attack would come at Calais, where the English Channel is narrowest. In actuality, General Dwight Eisenhower planned Operation Overlord aiming for the Normandy Peninsula on the morning of June 4, 1944.

Foul weather postponed the attack for two days. Just after midnight on June 6, 1944, three airborne divisions parachuted behind enemy lines to disrupt paths of communications. As the German lookout sentries scanned the English Channel at daybreak, they saw the largest armada ever assembled in history heading toward the French shore. There were five points of attack. Gold and Sword Beaches were taken by the British, and Juno Beach was captured by Canadian forces. The American task was to capture Utah and Omaha Beaches. The troops at Omaha Beach met fierce resistance and suffered heavy casualties. Still, by nightfall a beachhead had been established as German troops retreated. The successful invasion of 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 offloaded in support of the soldiers pushing forward through France.

After D-Day, the days of the German resistance were numbered. Paris was liberated in August 1944 as the Allies pushed slowly eastward. Meanwhile, the Soviet Union was moving into German territory as well. Desperate to put off what was clearly going to be a final defeat, Hitler launched a final unsuccessful counteroffensive 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 course of the Allied advance, rather than stopping it, and the Americans, British, and Free French found themselves racing the Soviets to Berlin by the spring of 1945.

Along the way, they encountered the depths of Nazi horrors when they discovered Hitler’s concentration camps. American soldiers saw humans that looked more like skeletons, gas chambers, crematoriums, and countless victims. Although American government officials were aware of atrocities against Jews, the full extent of the horror of the Holocaust of 12 million Jews, homosexuals, and anyone else Hitler had deemed deviant had been unknown to the Allies.

The Soviets entered Berlin first and discovered that the mastermind of all the destruction, Adolf Hitler, had committed suicide the day before. With little left to sustain any sort of resistance, the Germans surrendered on May 8, 1945, hereafter known as V-E Day, short for Victory in Europe.


Defeating Germany was only part of America’s mission.

Pearl Harbor was only the beginning of Japanese assaults on American holdings in the Pacific. Two days after attacking Pearl Harbor, they seized Guam, and two weeks after that they captured Wake Island. Before 1941 came to a close, the Philippines came under attack.

Led by General Douglas MacArthur, the Americans were hopeful they could hold the islands. A fierce Japanese strike proved otherwise. After retreating to the fortress at Corregidor, the United States had no choice but to surrender the Philippines. Before being summoned away by President Roosevelt, General MacArthur promised, “I shall return.”

After MacArthur escaped, the Japanese military forced Filipino and American prisoners of war to walk to at prison in Bataan. This 85-mile trip, remembered as the Bataan Death March, is emblematic of the cruelty unleashed by the Japanese military against prisoners. 16,000 souls perished along the way, and many more in the prisons where they languished in the years to come.

Primary Source: Photograph

The American aircraft carrier USS Yorktown listing to port at the moment a torpedo hit during the Battle of Midway. Anti-aircraft shells were exploding overhead.

In June 1942, Japan hoped to capture Midway Island, an American held base about 1,000 miles from Hawaii. The Japanese operation, like the earlier attack on Pearl Harbor, sought to eliminate the United States as a strategic power in the Pacific, thereby giving Japan a free hand in Asia. The Japanese hoped another demoralizing defeat would force the United States to capitulate by luring the American aircraft carriers into a trap. Their plan was handicapped by faulty Japanese assumptions about American airpower, and most significantly, by the fact that American cryptographers had broken the Japanese navy’s codes and knew the date and location of the planned attack, enabling the forewarned American commanders to prepare their own ambush.

Four Japanese and three American aircraft carriers participated in the battle. All four of Japan’s large fleet 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’s capacity to replace its losses, particularly aircraft carriers and well-trained pilots, rapidly became insufficient to cope with mounting casualties, while the United States’ massive industrial and training capabilities made losses far easier to replace. The Battle of Midway is widely considered the turning point in the Pacific War.

Primary Source: Photograph

Joe Rosenthal’s infamous photograph of Marines raising the flag at the top of Mount Suribachi on Iwo Jima.

After the Battle of Midway, the Americans slowly moved westward across the Pacific, retaking Japanese-held islands in a slow march toward Japan. Rather than taking every Japanese fortification spread across the islands of Micronesia and Melanesia, the United States selectively chose a path that would move American naval forces closer and closer to the Japanese mainland by targeting the least-fortified islands and bypassing those that would be harder to attack, leaving them cut off from communication and resupply. Using this Island Hopping strategy, General MacArthur led the advance toward Japan.

In October 1944, MacArthur fulfilled his promise and returned to the Philippines accompanied by a hundred ships. In the first half of 1945, Americans captured the island of Iwo Jima, which was then used to mount air raids on Japan.

The final island stronghold was the large island of Okinawa. The battle has been referred to as tetsu no ame, the “rain of steel” in Japanese because of the ferocity of the fighting, the intensity of Japanese kamikaze suicide airplane attacks, and the sheer numbers of Allied ships and armored vehicles that assaulted the island. The battle was one of the bloodiest in the Pacific, with approximately 160,000 casualties on both sides. Approximately 150,000 Okinawan civilians perished as well, roughly half of the pre-war population.

During the battle, Americans received word that President Roosevelt had died of a brain hemorrhage. 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 the outcome of the war in the Pacific. After watching the carnage that was the Battle of Okinawa, Truman’s first major decision would be how to resolve the war without having to invade the Japanese mainland.


Early in 1939, the world’s scientific community discovered that German physicists had learned the secrets of splitting a uranium atom. Fears spread over the possibility of Nazi scientists utilizing that energy to produce a bomb capable of unspeakable destruction.

Scientists Albert Einstein, who fled Nazi persecution, and Enrico Fermi, who escaped Fascist Italy, were now living in the United States. They agreed that the President must be informed of the dangers of atomic technology in the hands of the Axis powers. Fermi traveled to Washington in March to express his concerns to government officials. But few shared his uneasiness.

Einstein penned a letter to President Roosevelt urging the development of an atomic research program later that year. Roosevelt saw neither the necessity nor the utility for such a project, but agreed to proceed slowly. In late 1941, the American effort to design and build an atomic bomb received its code name: the Manhattan Project.

At first the research was based at only a few universities: Columbia University, the University of Chicago and the University of California at Berkeley. A breakthrough occurred in December 1942 when Fermi led a group of physicists to produce the first controlled nuclear chain reaction under the grandstands of Stagg Field at the University of Chicago.

After this milestone, government funds were allocated more freely, and the project advanced at breakneck speed. Nuclear facilities were built at Oak Ridge, Tennessee and Hanford, Washington. The main assembly plant was built at Los Alamos, New Mexico. Robert Oppenheimer was put in charge of putting the pieces together at Los Alamos. After the final bill was tallied, nearly $2 billion had been spent on research and development of the atomic bomb, and the Manhattan Project employed over 120,000 Americans.

Secrecy was paramount. Neither the Germans nor the Japanese could learn of the project. Roosevelt and Churchill also agreed that Stalin would be kept in the dark. Consequently, there was no public awareness or debate. Keeping 120,000 people quiet would be impossible. Therefore, only a small privileged cadre of inner scientists and officials knew about the final objective of the work. 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 near Alamogordo, New Mexico, scientists of the Manhattan Project readied themselves to watch the detonation of the world’s first atomic bomb. The device was affixed to a 100-foot tower and discharged just before dawn.

A blinding flash visible for 200 miles lit up the morning sky. A mushroom cloud reached 40,000 feet, blowing out windows of homes 100 miles away. When the cloud returned to earth it created a half-mile wide crater metamorphosing sand into glass. A bogus cover-up story was released, explaining that a huge ammunition dump had just exploded in the desert. Soon word reached President Truman in Potsdam, Germany that the project was successful. The world had entered the nuclear age.


When Harry Truman learned of the success of the Manhattan Project, he knew he was faced with a decision of unprecedented gravity. The capacity to end the war with Japan was in his hands, but it would involve unleashing the most terrible weapon ever known.

American soldiers and civilians were weary from four years of war, yet the Japanese military was refusing to give up their fight. American forces occupied Okinawa and Iwo Jima and were intensely fire bombing Japanese cities. But Japan still had an army of 2 million men stationed in the home islands guarding against invasion.

First, an Allied demand for an immediate unconditional surrender was made to the leadership in Japan. Although the demand stated that refusal would result in total destruction, no mention of any new weapons of mass destruction was made. The Japanese military command rejected the request for unconditional surrender.

Primary Source: Photograph

A photograph of downtown Hiroshima after the bombing. Everything that was not built of stone or concrete had been obliterated and burnt.

On August 6, 1945, a plane called the Enola Gay dropped an atomic bomb on the city of Hiroshima. Instantly, 70,000 Japanese citizens were vaporized. In the months and years that followed, an additional 100,000 perished from burns and radiation sickness.

The Japanese high command still refused to surrender and two days later, the Soviet Union declared war on Japan. On August 9, a second atomic bomb was dropped on Nagasaki, where 80,000 Japanese people perished.

On August 14, 1945, the Japanese surrendered. V-J Day, or Victory in Japan Day is marked on either August 14 or 15, depending on which day it was in the world when the news was announced, or sometimes on September 2, the day the official instrument of surrender was signed aboard the USS Missouri battleship in Tokyo Bay.


The decision to use the atomic bomb, and more specifically to use it on a city in which thousands of civilians would die has proved to be a lasting controversy.

Some military analysts insist that Japan was on its knees and the bombings were simply unnecessary.

Others have argued that the decision to use the bomb in Japan and not Germany was inherently racist. These critics question whether Truman would have been willing to use the bomb against White civilians.

Some charged that Truman’s decision was a barbaric act that brought negative long-term consequences to the United States. Looking into the future, Truman should have seen that unleashing nuclear weapons would lead to a dangerous arms race.

Other critics argued that American diplomats had ulterior motives in using the bomb. The Soviet Union had entered the war against Japan, and the atomic bomb could be read as a strong message for the Soviets to tread lightly. In this respect, 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. Regardless, the United States remains the only nation in the world to have used a nuclear weapon on another nation.

Related to the looming conflict with the Soviet Union, some felt that the atomic bomb was used to end the war quickly, before the Soviets would have a chance to invade Japan from the North. In this view, Truman wanted the United States to be the only nation to occupy Japan, unlike the way Germany had been divided up between the four Allied powers.

Truman himself stated that his decision to drop the bomb was purely military. A Normandy-type amphibious landing would have cost an estimated million casualties. Truman believed that the bombs saved Japanese lives as well as American. Prolonging the war was not an option for the President.

Some of his critics asked why Truman had not made some sort of demonstration of the bomb’s power by dropping it in the countryside, but the President rejected this idea. He knew there was no guarantee the Japanese would surrender if the test succeeded, and he felt that a failed demonstration would be worse than none at all. Even the scientific community failed to foresee 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 at his disposal. He could not imagine trying to justify the deaths of thousands of Americans when people found out he had a weapon that could have ended the war, but chose not to use it.

The ethical debate over the decision to drop the atomic bomb will probably never be resolved. The bombs did, however, bring an end to the most destructive war in history and the Manhattan Project that produced it demonstrated the possibility of how the nation’s resources could be mobilized in times of crisis.

However, the use of atomic weapons did unleash a dangerous arms race, and at nuclear standoff with the Soviet Union that lasted for 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 succumbed to. 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 aggressive attacks in Africa and the Soviet Union and eventually overran Berlin. In Asia, the war came to a close before the Americans invaded Japan itself.

Why was this the way the war ended? What brought about this conclusion, and not some other? Leadership? Technology? Numerical superiority? Ideals? Strategy?

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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