Johnston studied law with his step-father, Matthew Robinson, a prominent, well-read Rhode Island lawyer with a large private library.
[4] After building a successful reputation as an attorney, Augustus Johnston was appointed in 1754 and again in 1756 to assist in drafting legislation for General Assembly.
In October 1756 Johnston became a first lieutenant in a military regiment to be sent against Fort Crown Point during the French and Indian War.
On August 27, 1765 Johnston and two others who had supported the rights of the Parliament of Great Britain were hanged in effigy and the next day a mob damaged their homes and rioted outside the Newport Colony House.
[1] Augustus Johnston remained in Newport until July 18, 1776, but when he refused the Patriots' oath of allegiance he was ordered interned at South Kingstown for a time.