The Second World War was a global conflict that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing military alliances: the Allies and the Axis. It was the deadliest conflict in human history, with an estimated total death toll of 70 to 85 million people. The major participants were the United States, the Soviet Union, China, and the United Kingdom. These four powers are collectively referred to as the Big Four or the Grand Alliance.
The war had a profound impact on the course of global history. The United States emerged from the war as the world's leading superpower, while the Soviet Union became a major power. The war also led to the decolonization of Africa and Asia, and the creation of the United Nations.
Some of the key events of World War II include:
* The German invasion of Poland in 1939, which started the war.
* The Battle of Britain in 1940, which was a major turning point in the war.
* The Japanese attack on Pearl Harbor in 1941, which brought the United States into the war.
* The D-Day landings in 1944, which were a major Allied victory.
* The dropping of the atomic bombs on Hiroshima and Nagasaki in 1945, which led to the surrender of Japan and the end of the war.
The war had a profound impact on the world, and its legacy is still felt today.