Left without a ship after the peace in 1763, Elliot did not return to active service until 1767, when he was given command of the 60-gun , one of the Plymouth guardships. He also briefly became Member of Parliament for Cockermouth that year. He was moved to the newly built on 26 September 1770, but left her the following year and received no further commissions until 1777, when he took command of the 64-gun during the American War of Independence. He had been elected a Fellow of the Royal Society in January 1776, during his time ashore. He was promoted to commodore on 11 April 1778, and shortly afterwards took the Earl of Carlisle, George Johnstone and William Eden to North America to negotiate with the colonists as the Carlisle Peace Commission. After arriving at Delaware Elliot joined Richard Howe's command and took part in the relief of Rhode Island. He left the "Trident" towards the end of 1778 and returned to England and a brief spell of unemployment until his appointment to command the 74-gun in May 1779. It was about this time that he was made a Colonel of Marines, a post he held until 1787.