The New Mexico Territory, which included the areas which became the modern U.S. states of New Mexico and Arizona as well as the southern part of Nevada, played a role in the Trans-Mississippi Theater of the American Civil War. Both Confederate and Union governments claimed ownership and territorial rights over it. The first proposal dates from a conference held in Tucson that convened on August 29, 1856. The conference issued a petition to the U.S. Congress, signed by 256 people, requesting organization of the territory and elected Nathan P. Cooke as the territorial delegate to Congress.