In 1918 Germany lost the First World War. The Treaty of Versailles placed heavy burdens on the German people at a time when defeat had already been a bitter blow. Among the war veterans returning from the trenches was Adolf Hitler. On his return to Munich he worked for the German army, spying on new political parties. Among them was a small party known as the German Workers Party, which he ultimately joined in September 1919. In 1921 he became the leader of the now renamed National Socialist German Workers' Party - The Nazis.