World War II or the Second World War, often abbreviated

 as WWII or WW2, was a global war 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 powers.

Who started WW2?

On September 1, 1939, Hitler invaded Poland from the west; two days later, France and Britain declared war on Germany, beginning World War II.

The German tanks