After the American Revolutionary War, Hawkins was a New York militia officer, tavern owner, innkeeper, and postmaster.
[7] In December 1778, General George Washington's chief of intelligence and Culper Ring spymaster, Major Benjamin Tallmadge recruited Hawkins to bring messages from the Ring's chief spy in New York City, Abraham Woodhull, to Setuaket, New York where they would be forwarded to Tallmadge.
[10] By December 1778, Tallmadge set up couriers, at first Jonas Hawkins, then in the early summer mainly Austin Roe, who would take messages the 55 miles (89 km) between New York and Setauket to pass them to Brewster.
[11] Hawkins's task was to get the letters to Brewster who would pick up messages at Setauket and take them across the Sound to Tallmadge at Fairfield, Connecticut.
[12] In June 1779, Woodhull engaged Robert Townsend, who used the alias "Samuel Culper, Jr." to gather intelligence in New York City.
[12] According to widely accepted local and family tradition, Anna Strong signalled Brewster, who ran frequent trips with his whaleboats across the Sound on smuggling and military missions, that a message was ready.
[19][20][21] Historian Richard Welch writes that the tradition of the clothesline signal is unverifiable but it is known that the British had a woman at Setauket who fits Anna's profile under suspicion for disloyal activities.
[23] Townsend did not like taking the additional risk and was beginning to doubt Hawkins's reliability and to regret the destroyed messages.
[28] Major Jonas Hawkins inherited the Hawkins-Mount Homestead in Stony Brook, later known as the William Sidney Mount House, from his father.
[30] On June 25, 1810, Jonas Hawkins, Benjamin F. Thompson and Charles H. Havens founded a branch of the Tammany Society at Setauket.