The trails of roving Indians crossed these hills settled by German pioneers in 1846. A group of Mormons settled at Zodiac in 1847. Created February 23, 1848. Organized June 5, 1848. Named for Richard Addison Gillespie, a Texan from 1837, a defender of the Texas frontier, and captain in the Mexican War who fell at Monterrey, September 22, 1846. Fredericksburg, the county seat.