Canada

Created in 1863 as way to defend the British Colonies in North America of a possible United States invasion. Tension between the two always runned high and rumor of war were all always in the midst. In 1881, Canada served as a plateform for the British troops to enter the U.S and actually conquer Northern Maine. During the Great War it was conquered and became a U.S territory (Minus the Republic of Québec)

Ironicly the Quebecois/english rivalry that plague Canada in OTL doesn't exist.