Topic 7.13 Notes – World War II: Military

How the United States and the Allies Won World War II

Pearl Harbor brought the U.S. fully into the war on December 7, 1941. In his “date which will live in infamy” speech, FDR framed the attack as a direct assault on the nation. Within days, Germany and Italy declared war on the U.S., turning it into a true two-front war.

Americans increasingly saw the war as a fight for freedom and democracy against fascism and militarism. That idea mattered because it unified public support, and later it seemed even more justified when Allied troops uncovered Nazi camps and learned more about Japanese atrocities.

The best causation answer is never “D-Day won the war” or “the atomic bomb won the war.” Victory came from connected causes:

• U.S. productive power supplied ships, planes, tanks, food, and weapons on a huge scale.
• Soviet sacrifice on the eastern front destroyed much of Germany’s army.
• British survival gave the Allies a base for bombing and invading Europe.
• Coordinated Allied strategy kept these strengths working together.
• Axis weaknesses mattered too. Germany and Japan expanded too far, coordinated poorly, and could not match Allied resources.

The Main Reasons Allied Victory Was Possible

Allied cooperation and grand strategy

The major Allies were the United States, Great Britain, Soviet Union, and China. The Big Three were Franklin Roosevelt, Winston Churchill, and Joseph Stalin.

Even after Pearl Harbor, the Allies chose Germany first because Germany was the greater overall threat.

Industrial and geographic advantages

The U.S. became the arsenal of democracy. The Allies had bigger populations, more raw materials, more oil, and more ability to replace losses. Geography helped too:

• U.S. protected by oceans
• Britain served as a staging base
• Soviet Union absorbed massive German attacks

Technology and intelligence

Key tools included radar, sonar, codebreaking, aircraft carriers, long-range bombers, landing craft, submarines, proximity fuse, and penicillin. Codebreaking helped at Midway and against German communications. The point is not just invention. The Allies could mass-produce and deploy these tools. Britain’s role as a staging base also made major operations like the Normandy invasion possible.

D-Day landings in Normandy, June 6, 1944

Soviet and Axis roles

The Soviet victory at Stalingrad was indispensable. Germany made defeat more likely by invading the USSR and declaring war on the U.S. Japan also failed to destroy U.S. carriers at Pearl Harbor, which left America able to fight a long naval war.

The Campaigns That Broke the Axis

Europe and the Atlantic

• Operation Torch put Allied troops in North Africa; Axis forces there surrendered in 1943.
• The Allies invaded Sicily and Italy. Mussolini fell, but fighting continued.
• The Battle of the Atlantic secured supply lines through convoys, escorts, radar, sonar, and codebreaking.
• Strategic bombing hit Germany hard. Firebombing of Hamburg and Dresden raised moral questions.

D-Day, June 6, 1944, was Operation Overlord under Dwight D. Eisenhower:

1. Allies used deception so Germany expected Pas-de-Calais.
2. Airborne troops dropped behind German lines.
3. Troops landed at Utah, Omaha, Gold, Juno, and Sword.
4. They established a beachhead.
5. Paris was liberated in August 1944.

Germany’s last major western attack was the Battle of the Bulge. Hitler committed suicide, Germany surrendered on May 7, 1945, and V-E Day was May 8.

Pacific War

In the Pacific, the war began with rapid Japanese victories, then shifted as the U.S. fought its way back across the ocean.

Pacific island-hopping campaigns

Japan won early in the Philippines, Bataan, and Corregidor. The Bataan Death March became a symbol of Japanese brutality.

The tide turned in 1942:

• Coral Sea checked Japanese expansion.
• Midway destroyed four Japanese carriers.

The U.S. used island-hopping, shown on the map as advances across the central Pacific and through New Guinea and the Philippines:

1. Capture key islands
2. Bypass others
3. Advance along two routes under Chester Nimitz and Douglas MacArthur

Key campaigns were Guadalcanal, Gilbert and Marshall Islands, Marianas, Leyte Gulf, Philippines, Iwo Jima, and Okinawa. Submarines and bombing cut Japan off from resources. Kamikaze attacks and Okinawa showed how costly invasion would be.

Atomic Bombs, Atrocities, and the Meaning of Victory

The Manhattan Project brought together Leslie Groves, J. Robert Oppenheimer, Los Alamos, Oak Ridge, and Hanford. The Trinity test happened on July 16, 1945.

• Hiroshima on August 6 with Little Boy
• Soviet entry against Japan on August 8
• Nagasaki on August 9 with Fat Man
• Japan surrendered on August 15
• Formal surrender on September 2, or V-J Day

The debate still matters. Supporters said the bombs avoided invasion and shortened the war. Critics said Japan was already weakening, Soviet entry mattered, and the civilian destruction was morally unacceptable.

Atrocities reinforced Allied war aims:

• Holocaust
• liberation of camps such as Buchenwald and Dachau
• Nanjing Massacre
• Bataan Death March

About 16 million Americans served. Military service opened opportunities but also exposed inequality:

• Women served in WAC, WAVES, WASPs, and as nurses, mechanics, and radio operators.
• African Americans included the Tuskegee Airmen, 761st Tank Battalion, Doris Miller, and the Double V campaign.
• Japanese Americans served in the 442nd Regimental Combat Team.
• Native Americans included the Navajo Code Talkers.

Victory destroyed Axis regimes, revealed mass atrocities, began the nuclear age, and left the U.S. as a major global military power.