The North American Campaign of World War I was fought between Allied powers the Confederacy, the United States, and Great Britain on one side and the Central powers Mexico, Germany, Rebel Canada, California, and the Caribbean Federation on the other side. It began with the assassination of US president Theodore Roosevelt in July, 1914, sparking a war between Mexico and the United States. One by one, different states in North America picked sides and an all-out war soon erupted. Eventually, with massive German supported, the Central Powers was eventually victorious. Britain had to fight off a rebelion in Canada, and couldn't support her allies the way Germany did. The Confederacy collapsed, and the United States left the war in 1918. Britain signed an armistice with Germany also that year,