In 1866, after the
American Civil War ended, the number of settlers who used the trail en route to Montana gold fields increased. Around 1,200 wagons brought some 2,000 people to the city of Bozeman following the trail that year. The U.S. Army called a council at
Fort Laramie, which
Lakota leader
Red Cloud attended. The U.S. Army wanted to negotiate a right-of-way with the Lakota for settlers' use of the trail. As negotiations continued,
Red Cloud became outraged when he discovered that a regiment of U.S. infantry was already using the route without receiving permission from the Lakota nation. Thus
Red Cloud's War began. It was impossible for the army to undertake significant negotiations about the traffic through the western Powder River area and the future use of it with Red Cloud and any other Lakota. In 1851, the United States had acknowledged the tract belonged to the
Crow and was obliged by that. The Lakota tribe itself had recognized the same. That same year,
Nelson Story, a successful
Virginia City, Montana, gold miner originally from
Ohio, used the Bozeman Trail to successfully
drive about 1,000 head of
longhorn cattle into Montana. The U.S. Army unsuccessfully tried to turn Story back to protect the drive from Native American attacks, but Story brought cattle through to the
Gallatin Valley and formed one of the earliest significant herds in Montana's cattle industry. The U.S. Army established
Fort Reno,
Fort Phil Kearny and
Fort C. F. Smith along the route, staffed with troops meant to protect travelers. All three military posts were built west of Powder River, consequently outside the Lakota territory as recognized by the whites in the Fort Laramie Treaty. " ... the Sioux attacked the United States anyway, claiming that the Yellowstone was now their land". Native American raids along the trail and around the forts continued. When the Lakota annihilated a detachment under
William J. Fetterman at the
Fetterman Fight near Fort Phil Kearny on December 21, 1866, civilian travel along the trail ceased. On August 1, 1867, and August 2, 1867, U.S. forces resisted coordinated attempts by large parties of Lakota and Cheyenne to overrun
Fort C. F. Smith and
Fort Phil Kearny in the
Hayfield Fight and
Wagon Box Fight. The strikes and attacks on the soldiers "appeared to be a great Sioux war to protect their land. And it was - but the Sioux had only recently conquered this land from other tribes and now defending the territory both from other tribes and from the advance of white settlers". "In 1866, Red Cloud and his alliance of Lakotas, Cheyennes, and Arapahos fought for a territory they had dominated for only a few years". The Crows were all but pleased to see a part of their treaty-guaranteed land taken over by hereditary enemies, the Arapahoes, Cheyennes, and Lakotas. Despite resentment against the traffic on the Bozeman Trail, "the Crows still acted as allies of the harassed troops" in the forts. Later, by the 1868
Treaty of Fort Laramie, the U.S. recognized the
Powder River Country as unceded hunting territory for the Lakota and allied tribes. Most was located on former Crow treaty territory, now by conquest converted into new Lakota country. For a time the government used the treaty to shut down travel by European American settlers on the Bozeman Trail. President
Ulysses S. Grant ordered the abandonment of forts along the trail.
Red Cloud's War could thus be said to be the only Native American war in which Native Americans achieved their goals (if only for a brief time) with a treaty settlement essentially on their terms. By 1876, however, following the
Black Hills War, the U.S. Army reopened the trail. The U.S. Army continued to use the trail during later military campaigns and built a
telegraph line along it. ==Modern route==