Causes of World War I
One of the causes of World War I was that countries wanted to form empires.  This is called imperialism. From the late 1800s, the power of an empire is judged by its size. Britain had the largest empire, with lots of territories overseas, such as India. People would say "The sun never sets on the British Empire" because there were British holdings all over the world, so it was always day in some part of the empire. One way in which empires expanded their