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World War II (1939–1945)


Key Terms

terms Key Terms


Allied Powers

An alliance during World War II made up of the countries that opposed the aggression of Nazi Germany. Britain, France, the United States, and the Soviet Union were the most prominent members, although many other countries also joined.


Chancellor Adolf Hitler’s doctrine of German political union with Austria, which effectively enabled Germany to annex that nation in March 1938.


The British and French policy of conceding to Adolf Hitler’s territorial demands prior to the outbreak of World War II. Associated primarily with British prime minister Neville Chamberlain, the appeasement policy enabled Hitler to systematically take over the territories of several neighboring countries.

Axis Powers

The collective term for Germany, Italy, and Japan’s military alliance in opposition to the Allied Powers. Several smaller countries in Eastern Europe also became members of the Axis Powers temporarily.

Battle of Britain

An extended campaign from July 1940 to the spring of 1941 in which British air forces fought off wave after wave of German bombers and denied Germany in its quest to attain air superiority over Britain. Although major cities in England sustained heavy damage, the British resistance forced Germany to abandon its plans to invade across the English Channel.

Battle of the Coral Sea

A battle from May 4–8, 1942, in which U.S. naval forces successfully protected the Allied base at Port Moresby, New Guinea, the last Allied outpost standing between the Japanese onslaught and Australia. The battle, which caused heavy losses on both sides, was the first naval battle in history fought exclusively in the air, by carrier-based planes.

Battle of El-Alamein

An October and November 1942 battle that was the climax of the North African campaign. A resounding victory by the British over the Germans, the battle paved the way for the Allied takeover of North Africa and the retreat of German forces back across the Mediterranean.

Battle of Guadalcanal

A campaign from August 1942 to February 1943 in which U.S. Marines fought brutal battles to expel Japanese forces from the Solomon Islands, a strategically important island chain in the South Pacific near Australia.

Battle of Iwo Jima

A battle in February and March 1945 in which U.S. forces took Iwo Jima, a small but strategically important island off the Japanese coast. During the battle, an Associated Press photographer took a world-famous photograph of U.S. Marines raising the American flag on the summit of Mt. Suribachi.

Battle of Midway

A battle from June 3–6, 1942, in which U.S. naval forces severely disabled the Japanese fleet at Midway Island in the Pacific. Coming close on the heels of the Battle of the Coral Sea, the Battle of Midway forced Japan into defensive mode and turned the tide of the war in the Pacific theater.

Battle of Okinawa

The last large-scale battle in the Pacific theater, in which U.S. forces invaded the Japanese home island of Okinawa. The battle was very bloody, killing at least 100,000 Japanese soldiers and 80,000 to 100,000 Japanese civilians.

Battle of Stalingrad

A brutal, five-month battle between German and Soviet forces for the important industrial city of Stalingrad that resulted in the deaths of almost 2 million people. The battle involved very destructive air raids by the German Luftwaffe and bloody urban street fighting. In February 1943, despite direct orders from Hitler forbidding it, Field Marshal Friedrich Paulus surrendered the German forces to the Red Army.


Literally “lightning war,” the term for Hitler’s invasion strategy of attacking a nation suddenly and with overwhelming force. Hitler applied the blitzkrieg strategy, with varying degrees of success, to the German invasions of Poland, France, and the Soviet Union.


June 6, 1944, the day on which the Allied invasion of France via the Normandy coast began.


A system of government dominated by far-right-wing forces and generally commanded by a single dictator. Several Fascist governments were established in Europe in the early twentieth century, most notably those led by dictators Adolf Hitler of Germany, Benito Mussolini of Italy, and Francisco Franco of Spain.

“Final Solution”

The Nazi’s euphemistic term for their plan to exterminate the Jews of Germany and other German-controlled territories during World War II. The term was used at the Wannsee Conference of January 1942, in which Nazi leaders planned the Holocaust but made no specific mention of the extermination camps that ultimately killed millions.


The brutal Nazi secret police force, headed by the infamous Hermann Göring. The Gestapo was responsible for the relocation of many European Jews to Nazi concentration camps during the war.


Literally “living space,” Adolf Hitler’s justification for Germany’s aggressive territorial conquests in the late 1930s. Based on the work of a previous German ethnographer, Hitler used the idea of lebensraum to claim that the German people’s “natural” territory extended beyond the current borders of Germany and that Germany therefore needed to acquire additional territory in Europe.


The German air force, which was used heavily in campaigns such as the Battle of Britain in 1940.

Manhattan Project

The code name for the U.S. government’s secret program to develop an atomic bomb. Begun in 1942, the Manhattan Project utilized the expertise of world-famous physicists, including Albert Einstein and Enrico Fermi, to develop the weapon. It finally succeeded in conducting the first successful atomic bomb test in July 1945 at Alamogordo, New Mexico. After a difficult decision by President Harry S Truman, U.S. forces dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki in August 1945, prompting Japan’s surrender.

Munich Agreement

A September 30, 1938, agreement among Germany, Britain, Italy, and France that allowed Germany to annex the region of western Czechoslovakia called the Sudetenland. The Munich Agreement was the most famous example of British prime minister Neville Chamberlain’s policy of appeasement prior to World War II.

Operation Barbarossa

The code name for the German invasion of the Soviet Union in 1941, which Hitler predicted would take only six months but ended up miring the German armies for more than two years.

Operation Overlord

The code name for the Allied invasion of France in 1944, which commenced on the beaches of Normandy and ultimately was successful in liberating France and pushing German forces back east to their own territory.


In German, Schutzstaffel (“protection detachment”), the elite German paramilitary unit. Originally formed as a unit to serve as Hitler’s personal bodyguards, the S.S. grew and took on the duties of an elite military formation. During World War II, the Nazi regime used the S.S. to handle the extermination of Jews and other racial minorities, among other duties. The S.S. had its own army, independent of the regular German army (the Wehrmacht), to carry out its operations behind enemy lines.

V-E Day

May 8, 1945, the day on which the Allied forces declared victory in Europe.

V-J Day

August 15, 1945, the day on which the Allied forces declared victory over Japan.

Wannsee Conference

A January 1942 conference during which Nazi officials decided to implement the “final solution” to the “Jewish question”—a euphemism for the extermination of European Jews and other minorities at concentration camps in eastern Europe.


The term used for regular German army.

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