Dear Ms. Keathley,
Thank you for posting your request on History Hub!
We suggest that you request a search from the South Carolina Department of Archives and History for resources such as photographs, maps, estate records, wills, biographies, journals, and local histories that may help you research the ancestry of Prince Johnson. We also suggest that you search the Slave Data Collection index and review the FamilySearch Research wiki for Hampton County, South Carolina Genealogy
In addition, the National Archives African American Heritage website, the FamilySearch research wiki on African American Resources for South Carolina as well as the document Federal Records that Help Identify Former Slaves and Slave Owners may be useful.
We hope this is helpful. Best of luck with your family research!