World War 1 began on July 28, 1914 and lasted until November 11, 1918. World War 1 was mostly cause by an assassination. The United States decided to join the war because the Germans sunk one of our ships and we could not stay neutral forever, especially when our allies were on the verge to losing the war. Our allies included Spain, Russia, Italy, etc. The Central Powers included, Germany, Hungary, Bulgaria, etc. Many advancements were made during the war including, medical advancements, tanks, assault rifles, grenades, etc. Mobilization occurred in the United States so that we could be prepared for War. It was also the beginning of mass production. By the time World War 1 ended in the defeat of Central powers, more than nine million soldiers have been killed and twenty-one million wounded.