In brief, he spoke a localized version of the dialect of Southern England. By the time of the Revolutionary War both the American version and the original English had begun modifying. Here is a brief excerpt from a very interesting piece worth reading in its entirety for a clearer understanding:
“Let’s move on to a very different dialect. From 1642–1675 the Royalists, also called Cavaliers, fled from the south and southwest England with their indentured servants and settled in Virginia when the English Civil War against Charles I began. They brought with them their south England drawl (a drawing out of the vowels); they also brought such phrases as aksed (instead of asked), and ain’t (instead of isn’t). Royalists later settled the Carolinas as well. Southern English speech laid the foundation for the development of American Tidewater speech, or Coastal Southern English.
A large number of features distinguish southern dialects as a group from their cousin dialects in the American north, as well as from modern British dialects in the south of England.
—the classic Southern drawl, caused when vowels become long or diphthongalized: house = ha:wse, eggs = ai:gz; some words even contain triphthongs: flowers. [fla:ierz]
—loss of final t, d after another consonant: an(d), tol(d)
—first syllable accented (rather than the second) in such words as: guitar, insurance, July, police, elope, etc.
—yall for you all
—bucket, not pail”