World War I began on July 28, 1914 and it broke out because Austria's Archduke, Franz Ferdinand, was assassinated. When World War I started it was between the allied forces, France, the United Kingdom and Russia, and the Central powers, Germany and Austria-Hungary.

The US got into the war for two reasons. The first was that Germany sank a British ship which the US considered neutral and which help 159 american passengers. The second reason was the Zimmerman telegram which was from Germany to Mexico that promised parts of the US territory to return to Mexico once Germany started the war with the US. On April 6,1917 the US declared war on Germany.

World War I ended on June 28, 1919 in Belgium after Germany invaded it.