Fort Laramie was the main outpost of the U.S. Government on the Northern Plains and served as an official meeting ground between the United States of America and the sovereign tribes of the Northern Plains. The first great treaty negotiation, the Treaty of 1851, proved too large for Fort Laramie and quickly moved to Horse Creek in western Nebraska, where more than 10,000 participants made it the largest gathering of Plains Indians in the 19th century. For the next 17 years Fort Laramie functioned as an unofficial U.S. embassy to the Northern Plains, where U.S. Peace Commissioners and tribal leaders including Smoke, Red Cloud, Man Afraid of His Horses, and Spotted Tail conducted affairs of state. Preparations for meetings and negotiations at the fort were as much a part of military routine as wood cutting parties and guard duty. As the Bozeman Trail crossed lands protected by the 1851 treaty and the Transcontinental Railroad progressed west, hostilities increased in the 1860s and negotiations at Fort Laramie grew in importance. Several peace councils met between 1866 and 1868, culminating in three treaties signed there in the spring of 1868 between the Federal Government and the Cheyenne and Arapaho, the Crow, and 10 Sioux bands. These treaties established the reservation system on the Northern Plains and continue to serve as foundational legal documents. Soon afterward, the treaties separated Fort Laramie from the various tribes and ended the post's role as a council site. In good weather, treaty negotiations were held on open ground on the east side of the Laramie River, which served as a gathering place and campground for emigrants, soldier, and peace councils; in bad weather, negotiations moved to the large post commissary and quartermaster warehouses on the northeast end of the post.