Red Cloud was one of the most important leaders of the Oglala Lakota from 1868 to 1909. He was one of the most capable Native American opponents whom the United States Army faced in its mission to occupy the western territories, defeating the United States during Red Cloud's War, which was a fight over control of the Powder River Country in northeastern Wyoming and southern Montana. The largest action of the war was the Fetterman Fight, with 81 U.S soldiers killed; it was the worst military defeat suffered by the Army on the Great Plains until the Battle of the Little Bighorn 10 years later.
After signing the Treaty of Fort Laramie, Red Cloud led his people in the important transition to reservation life. Some of his opponents mistakenly thought of him as the overall leader of the Sioux groups, but the large tribe had several major divisions and was highly decentralized. Bands among the Oglala and other divisions operated independently, though some individual leaders were renowned as warriors and highly respected as leaders, such as Red Cloud.