During the period from 1784 to 1821, one of the major causes of friction along the St. Marys River, the dividing line between the United States and East Florida, was the frequent disappearance of Negro slaves, usually fleeing from the American bank of the river into the sparsely populated Spanish colony where they hoped to find a refuge with the Indian population or among the freed Negroes and mulattoes in St. Augustine. Frequent arrangements were made by the authorities on both sides to return the runaways as soon as possible to their legitimate owners to avoid unnecessary diplomatic wrangling.
Murdoch, Richard K.
"Documents Pertaining to the Georgia-Florida Frontier, 1791-1793,"
Florida Historical Quarterly: Vol. 38
, Article 6.
Available at: https://stars.library.ucf.edu/fhq/vol38/iss4/6