In 1854, the Kansas Territory was organized; and in 1861 Kansas became the 34th U.S. state. Ellsworth County was established February 26, 1867. The county was named after the old Fort Ellsworth, named in honor of 2nd Lieutenant Allen Ellsworth of the 7th Iowa Cavalry (Company H), who supervised construction of the fort in 1864 during the American Civil War. On November 17, 1866, the fort was renamed Fort Harker in honor of General Charles Garrison Harker who had died on June 27, 1864, from wounds received in an abortive offensive action in the Battle of Kennesaw Mountain. The fort was subsequently moved to a new site about one mile to the northeast, and the old fort's remaining buildings were ordered torn down in June 1867.