In September 1939, Britain entered into what would become the world's most devastating war ever. Lasting six years, it was a war that changed the lives of millions of people around the globe. Find out what happened during this hugely important historical event with National Geographic Kids’ ten facts...
1) World War II was a battle between two groups of countries - the 'Allies' and the 'Axis'. The major Allied Powers were Britain, France, Russia, China and the United States. The major Axis Powers were Germany, Italy and Japan.
2) Before World War II began, Germany was ruled by a man named Adolf Hitler and the Nazi Party, who wanted Germany to rule Europe. To gain more land and power, on 1 September 1939 German troops invaded Poland. After Hitler refused to stop the invasion, Britain and France declared war on Germany - World War II had begun.
3) During the course of the war, German forces advanced through Europe. By the summer of 1941 they had invaded France, Belgium, Holland, Luxembourg, Denmark, Norway, Greece, Yugoslavia* and the USSR*.
4) In Germany, millions of people were imprisoned and killed because they did not fit Hitler's image of the 'perfect' German. He wanted to create what he thought was the 'best' and strongest race - and to the Nazi Party, this excluded certain groups, such as Jews, Gypsies and those with physical and mental disabilities. In an attempt to eliminate a 'racial enemy' outside of Germany, such groups were also persecuted in the countries invaded by German forces.
5) The group most heavily targeted by the Nazis were the Jews. Around six million Jewish people were killed during World War II in one of history’s most terrible events - the Holocaust. Racist in his views, Hitler blamed Jewish people for Germany losing World War I and claimed they were dangerous to German people and society.
6) Around the same time that Germany fought for power in Europe, Japan wanted to control Asia and the Pacific. In 1937 (before World War II had officially begun) under Emperor Hirohito, Japan attacked China, bringing the two nations into years of conflict.
7) The US didn't join the war until 1941, when Japan attacked the United States Naval Base at Pearl Harbor in Hawaii. On 8 December 1941 (the day following the attack on Pearl Harbor), the US declared War on Japan and, in turn, its German allies.
8) Some countries remained 'neutral' in World War II and chose not to join either side. Such countries were Spain, Sweden and Switzerland.
9) In 1944, an Allied army crossed from Britain to free France from Nazi rule. One year later, Allied armies invaded Germany, forcing the Germans to surrender on 8 May 1945. After nuclear attacks on Japan's major cities Hiroshima and Nagasaki, Japan also surrendered to Allied forces in August the same year. World War II had ended.
10) It's estimated that around 64 million people died in World War II - that's more than the entire population of the United Kingdom.