Rocky Hill, originally known as Zodiac, was on the Pedernales River four miles southeast of Fredericksburg in southern Gillespie County. Zodiac was founded in 1847 by a group of 200 Mormons under Lyman Wight, who had sought and received John O. Meusebach's permission to settle near Fredericksburg. The Mormons quickly built the first gristmill and sawmill in Gillespie County and supplied the Germans with seeds, flour, and lumber; they also helped build Fort Martin Scott in 1848. The 1850 census showed Zodiac with a population of 161. The Mormons left Gillespie County after a flood destroyed their mills in 1853 but retained ownership of a one-acre cemetery in Zodiac, at which Wight was later buried. Shortly after the Mormons departed, a group of English, German, and Danish families moved in. Before and during the Civil War the area was the site of the only Gillespie County cotton plantation to use slave labor; descendants of the slaves still owned land there as late as 1947. The town was renamed Rocky Hill after the local school, built in 1885.