 Fullmer visited his family, who had moved from Ohio, in Nauvoo, Illinois in 1839 and was baptized by Smith on July 29, 1839 before returning to Nashville to assist his wife and their two daughters, Lavina Elizabeth and Johanna, in moving to Nauvoo.While living in Nauvoo, Fullmer was closely associated with Smith and served for a while as his private secretary.While living in Nauvoo, Fullmer left to serve as a missionary to Pennsylvania in 1842 and Vermilion County, Illinois in 1845.