After the American Civil War, the Army decided to expand Fort Snelling and make it the headquarters for the Department of the Dakotas. In 1871 the fort was bought back from Franklin Steele, a local businessman who had envisioned building a city on the site. In 1878 a new building program was started, including brick barracks that came complete with indoor plumbing and central heating-the first barracks on the post to receive those modern features.
Many of the surviving buildings date from this burst of growth, from 1878 to 1892. The headquarters building with its distinctive clock tower was erected in 1879 to 1880 and briefly held the headquarters for the Department of the Dakotas. The businessmen in St. Paul missed the boost the officers brought to the town's economy, so in the mid 1880s they donated land for a new head headquarters downtown. After that the HQ was used to administer only the fort and not the department.
For the rest of the 1800s the fort was used as a supply base for posts farther out on the frontier and as a base for some black regiments, which the Indians called Buffalo soldiers because their hair resembled buffalos.