U.S. History

World War I was called the War to End All Wars – but World War II was far worse.

Throughout human history, the end of one war has usually proven to be the makings of the next. So it was with “The Great War,” World War I. The peace negotiations held in Paris between January and June 1919 transformed geopolitical relationships and territorial boundaries in a way that set the stage for World War II. As Margret MacMillan explained in her history of those meetings, Paris 1919: Six Months That Changed the World, “Those first six months are the ones that count when the key decisions were taken, and the crucial chains of events were set in motion.”

World War I Created the Conditions for World War II

World War I resulted in a horrific loss of life. Four major empires ceased to exist after the Armistice was signed on November 11, 1918, ending the fighting. The Austro-Hungarian Empire, the German Empire, the Ottoman Empire, and the Russian Empire all, for one reason or another, disappeared after World War I.

Germany, in particular, carried the majority of the post-World War I sanctions. The country was disarmed, discredited in the community of nations, and humiliated as a people. A nation that was economically a failing state, the country was ripe for a leader capable of breathing life into socially and culturally dispirited people. Enter Adolf Hitler and the Third Reich with a message of German and Aryan race supremacy that appealed to the German people. Hitler was a charismatic and manipulative speaker who created an evil but persuasive story that exploited the German people’s resentment, and a dictator and ruthless war machine emerged. Hitler set about a conquest of Germany’s neighbors in 1939 with what was called a lightning war or Blitzkrieg.

Germany quickly occupied Poland, France, Belgium, Netherlands, and Luxembourg. The excuse Hitler used was that Germany needed lebensraum, a German word for living space, to achieve his expansionist aims. Following the fall of France, Germany began a relentless air attack on England, that became the “Battle of Britain,” a prelude to an invasion. However, Hitler did not count on the tenacity of the British people and the airmanship of the Royal Air Force. The Third Reich was never able to mount an invasion of Britain. Seeing an opportunity to improve Italy’s fortunes, the Italian leader Benito Mussolini joined Hitler in what was then called the Axis powers.

At the same time, in the Pacific, Japan also felt poorly treated in the outcome of the Paris peace process, with a festering bitterness that prompted an expansionist doctrine. Japan joined the Axis powers, invaded China, and began conquering Pacific islands. On December 7, 1941, Japanese aircraft carrier-based bombers and fighter planes attacked Pearl Harbor, Hawaii, in what then-President Franklin Roosevelt called “a day that will live in infamy.” The US declared war on Japan immediately, and on December 11, 1941, Germany declared war on the US. America was officially in World War II.

Breaking an agreement not to fight with Russia, Germany invaded the Soviet Union in June 1941, which opened a second Eastern Front for the German forces, which saw early victories. Still, the invasion came to a halt at Stalingrad, where the German ground forces began a slow retreat and did not again gain an advantage against the Russians.

The US Armed Forces, though building in capability, were the least prepared for a world war. President Roosevelt knew attempting to fight in the Pacific and Europe with an unseasoned military would be costly. So, America adopted a “Europe First” strategy. This is not to say the US military abandoned the war in the Pacific. In fact, following the attack on Pearl Harbor, US naval forces met and defeated the Japanese at the Battle of Midway Island, and a flight of B-25 bombers attacked Tokyo. However, the momentum to win in the two regions would focus first on Europe. To create an experienced and hardened fighting force, Roosevelt elected to engage the German army in North Africa, then invade Sicily, followed by mainland Italy. In the meantime, US forces would build in England for a D-Day invasion of France.

Momentum Turned in Favor of the Allies

The tide turned against the Axis powers with key Allied victories. The British defeat of the Germans at El Alamein in North Africa, Russia stopping German advances at Stalingrad, and the US naval victory at Midway were crucial in the eventual fall of Germany and Japan. The victorious Allied invasion of Normandy on June 6, 1944, was a fatal blow to Germany, and less than a year later, after fierce battles, Germany surrendered on May 8, 1945. However, war continued in the Pacific. It would take the dropping of atomic bombs on the Japanese cities of Hiroshima and Nagasaki in August 1945 to end World War II. That was the first – and, so far, the last – use of nuclear weapons in war.

The results of World War II were over 70 million dead, including civilians from bombing raids, starvation, and genocide. As History.com described the war, “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.” Two undeniable global superpowers emerged at the war’s end: the United States and the Soviet Union. An “Iron Curtain” descended, separating the US and its Western Allies and the Soviet Union and its Warsaw Pact partners. Just as the end of World War I led directly to World War II, that second World War then resulted in a new kind of conflict: The Cold War.

1. What happened immediately after World War I set the stage for World War II and made it inevitable.
2. Italy and Japan joined Hitler’s Germany, creating the alliance known as the Axis powers. Eventually, 50 countries were involved in the war.
3. The Japanese attacked Pearl Harbor on December 7, 1941, which drew the US into the war and led, eventually, to the first and only use of nuclear weapons in war.