The causes of the Indian wars, battles and conflicts, including the Battle of Bighorn, were generally because of the opening of Indian lands to colonization, the conquest of the Native American Indians or the history of forced relocation to Indian reservations. Interesting facts and information about the significance, specific events and famous leaders of the Battle of Bighorn. The combatants of the Battle of Bighorn were the US Cavalry and Sioux, Cheyenne & Arapaho, Indians.