This question refers to the Stono Rebellion of 1739, an uprising of enslaved men and women in Low Country South Carolina. James Oglethorpe, the English reformer who founded Georgia as a debtor colony and a buffer between English South Carolina and Spanish Florida, described the event in a letter to the company that backed the Georgia colony, then in its infancy. The letter is reprinted in the 1999 anthology A Documentary History of Slavery in North America, edited by Willie Lee Rose.
In the letter, Oglethorpe stressed the English perception that the revolt had its origins in Spanish machinations. Specifically, Spanish authorities offered asylum to any enslaved people that made their way to Florida and were willing to convert to Roman Catholicism. Many of the identified leaders among the Stono rebels were Catholic, hailing from Angola, so Florida was a very enticing destination—even before the proclamation, many enslaved people had made their way to that colony.
Spain, of course, had its own reasons for welcoming enslaved Carolinians. They hoped to grow the population of Florida and to weaken and destabilize the colonies of their English rivals.
By publicizing this incident, Oglethorpe hoped to gain public support for his struggling colony. Slavery was banned in Georgia under its charter: the better for making it a buffer zone where enslaved fugitives could be easily captured as well as a haven for English debtors. He also probably hoped to highlight his own role in recapturing enslaved men who had made their way to St. Augustine.