World War II (1939-1945)

Nazi Germany launched a surprise invasion of Poland on September 1, 1939, using Blitzkrieg tactics of coordinated air and ground assaults. Britain and France declared war on Germany on September 3, marking the official beginning of World War II in Europe. The Soviet Union invaded eastern Poland on September 17 under the secret protocols of the Molotov-Ribbentrop Pact. Warsaw fell on September 27, and organized Polish resistance ended by October 6.

In May-June 1940, Germany launched a blitzkrieg invasion of France through the Ardennes, bypassing the Maginot Line. The British Expeditionary Force was trapped at Dunkirk and evacuated over 338,000 soldiers in Operation Dynamo. France signed an armistice with Germany on June 22, 1940, and German forces occupied northern France.

The Battle of Britain was the first major military campaign fought entirely by air forces. From July to October 1940, the German Luftwaffe launched sustained aerial attacks against British shipping, airfields, and cities to gain air superiority for a planned invasion, Operation Sea Lion. The Royal Air Force successfully defended British airspace using radar-directed interceptions. Hitler postponed the invasion indefinitely on September 17. The battle demonstrated the decisive role of air power and radar in modern warfare.

Location: United Kingdom

Nazi Germany launched Operation Barbarossa on June 22, 1941, the largest military invasion in history. Three German army groups advanced along an 1,800-mile front toward Leningrad, Moscow, and Ukraine. Despite encircling and capturing over 3 million Soviet soldiers by December, the offensive stalled before Moscow in the winter. The failure to achieve a quick victory opened a protracted war of attrition that ultimately became the decisive theater of the European war.

Location: Soviet Union (Eastern Front)

The Imperial Japanese Navy launched a surprise attack on the US naval base at Pearl Harbor on December 7, 1941. Over 350 Japanese aircraft in two waves sank or damaged eight US battleships, destroyed 188 aircraft, and killed 2,403 American personnel. The United States declared war on Japan on December 8, entering World War II. Germany declared war on the United States on December 11, bringing the US fully into the European theater as well.

Location: Pearl Harbor, Hawaii, United States

From June 4-7, 1942, the U.S. Navy decisively defeated the Imperial Japanese Navy at the Battle of Midway. American dive bombers sank four Japanese aircraft carriers — Akagi, Kaga, Soryu, and Hiryu — while losing only the USS Yorktown. The battle marked a turning point in the Pacific theater and ended Japanese naval offensive capability.

The Battle of Stalingrad, from August 23, 1942, to February 2, 1943, was a brutal urban battle between German and Soviet forces for control of the city on the Volga River. Widely regarded as the turning point of the war in Europe, the battle saw the German 6th Army encircled by a Soviet counteroffensive, Operation Uranus, in November 1942. Field Marshal Friedrich Paulus surrendered on February 2. The battle resulted in an estimated 2 million total casualties, making it one of the deadliest battles in history.

Location: Stalingrad, Soviet Union (now Volgograd, Russia)

On June 6, 1944, Allied forces under General Dwight D. Eisenhower launched Operation Overlord, the largest amphibious invasion in history. Approximately 156,000 troops from the United States, Britain, Canada, and other Allied nations landed on five Normandy beaches codenamed Utah, Omaha, Gold, Juno, and Sword. Despite heavy casualties on Omaha Beach, the Allies secured a foothold in Nazi-occupied France. The invasion opened the long-awaited Western Front, leading to the liberation of Paris on August 25 and the eventual defeat of Nazi Germany.

Location: Normandy, France

Beginning on December 16, 1944, Germany launched a surprise winter offensive through the Ardennes forest in Belgium and Luxembourg, aiming to split Allied forces and capture the port of Antwerp. The month-long battle became the largest and bloodiest battle fought by U.S. forces in World War II, with over 80,000 American casualties. The German offensive was defeated by late January 1945, depleting Germany's strategic reserves.

Nazi Germany surrendered unconditionally on May 7, 1945, at the Supreme Headquarters Allied Expeditionary Force in Reims, France, with a second signing in Berlin on May 8 at the Soviet Union's request. The surrender followed Adolf Hitler's suicide on April 30, the fall of Berlin to Soviet forces on May 2, and the collapse of organized German resistance. May 8 is celebrated as Victory in Europe (V-E) Day, ending the European theater of the war after 5 years and 8 months.

Location: Berlin, Germany / Reims, France

The United States dropped atomic bombs on Hiroshima on August 6 and Nagasaki on August 9, 1945 - the first and only use of nuclear weapons in armed conflict. The Hiroshima bomb killed an estimated 70,000-140,000 people; the Nagasaki bomb killed 40,000-70,000 by the end of 1945. Japan announced its surrender on August 15 and formally signed the Instrument of Surrender aboard the USS Missouri on September 2, 1945, ending World War II. The war's total death toll is estimated at 60-75 million people.

Location: Hiroshima and Nagasaki, Japan