The conflicts over the possession of land between the Indians and the 'American' settlers led the Americans in 1855, by the 'treaties' at the Walla Walla Council, to coerce not only the Cayuse, but also the Walla Walla and the Umatilla tribes, to the Umatilla Indian Reservation in northeastern Oregon; fourteen other tribal groups to the Yakama Indian Reservation in southern Washington State; and the Nez Perce to a reservation in the border region of Washington, Oregon and Idaho. That same year, gold was discovered in the newly established Yakama reservation and white miners encroached upon these lands. The tribes - first the Yakama, eventually joined by the Walla Walla and the Cayuse - united together to fight the Americans in what is called the Yakima War. The U.S. Army sent troops and a number of raids and battles took place. In 1858, the Americans, at the Battle of Four Lakes, defeated the Indians decisively. In a newly imposed 'treaty,' tribes were, again, confined to reservations.