Proper noun

Singular World War II

Plural -

World War II

1. The war from 1939 to 1945 of the Allied forces of the (British) Commonwealth, France, the United States, the Soviet Union, Canada, and China against the Axis Powers, including Germany, Italy, and Japan.

Synonyms

• Second World War (less common)

Related terms

• world war
• World War I
• World War III

World War II, or the Second World War (often abbreviated WWII or WW2), was a global military conflict which involved a majority of the world's nations, including all of the great powers, organized into two opposing military alliances: the Allies and the Axis. The war involved the mobilization of over 100 million military personnel, making it the most widespread war in history. In a state of "total war", the major participants placed their entire economic, industrial, and scientific capabilities at the service of the war effort, erasing the distinction between civilian and military resources. Over seventy million people, the majority of whom were civilians, were killed, making it the deadliest conflict in human history.

The start of the war is generally held to be September 1, 1939, with the German invasion of Poland and subsequent declarations of war on Germany by most of the countries in the British Empire and Commonwealth, and by France. Many countries were already at war before this date, such as Nationalist China and Japan in the Second Sino-Japanese War, and many who were not initially involved joined the war later, as a result of events such as the German invasion of the Soviet Union (Operation Barbarossa), and the attacks on Pearl Harbor and British and Dutch colonies in Southeast Asia.

In 1945 the war ended in a victory for the Allies. The Soviet Union and the United States subsequently emerged as the world's superpowers, setting the stage for the Cold War, which lasted for the next 46 years. The United Nations was formed in the hope of preventing another such conflict. The acceptance of the principle of self-determination accelerated decolonization movements in Asia and Africa, while Western Europe itself began moving toward integration.

World War II or the Second World War, often abbreviated as WWII or WW2, was a worldwide military conflict; the amalgamation of two separate conflicts, one beginning in Asia, 1937, as the w:Second Sino-Japanese War and the other beginning in Europe, 1939, with the invasion of Poland. It is regarded as the historical successor to World War I.

This global conflict split a majority of the world's nations into two opposing military alliances: the Allies and the Axis. Spanning much of the globe, World War II resulted in the deaths of over 70 million people, making it the deadliest conflict in human history.