On May 14, 1796, Dr. Edward Jenner administered the first inoculation that would eventually lead to the smallpox vaccination. But much of the credit goes to an enslaved man, Onesimus, who 90 years earlier introduced the concept of variolation.
Sources:
https://www.history.com/this-day-in-history/jenner-tests-smallpox-vaccine
https://www.history.com/news/smallpox-vaccine-onesimus-slave-cotton-mather
https://www.who.int/health-topics/smallpox#tab=tab_1
