 Fort <unk> was built in 1853 – 1854 near the Dakota reservation in southwestern Minnesota , near modern New Ulm . It was named by U.S. Secretary of War Jefferson Davis in honor of three army officers named <unk> who had died in the Mexican @-@ American War . The fort was created to watch over the Minnesota River Valley , in addition to the larger frontier . It replaced Fort <unk> in Iowa , which was decommissioned during the same period . The fort operated as a military post until 1867 . 
