Son of Samuel Graves, he was thought to have been born in Northern Ireland where his grandfather, Captain James Graves, who married a daughter of Sir John Herdman of Stannington, lived, before he was robbed of his regiment's wages and murdered in his bed. Graves joined the Royal Navy in 1732. Made lieutenant in 1739, he participated in the 1741 expedition against Cartagena, serving on the frigateNorfolk, under his uncle and future admiral, Captain Thomas Graves. Samuel Graves's cousin Thomas, Captain Graves's son and also future admiral, served alongside him on the third-rateship-of-the-lineNorfolk. Promoted to command of the sloopBonetta in 1743, Graves served in the West Indies until 1747, commanding Ripon's Prize, and, later, Enterprise.
Seven Years' War
In 1756 Graves rose to command Duke. Two years later, Graves returned to the command of Duke, serving again under Hawke in the Battle of Quiberon Bay on 20 November 1759. He continued in command of Duke until his promotion to rear admiral in October 1762.
In October 1770 Graves rose to vice admiral, and in July 1774 assumed command of the North American Station. Graves's orders were vague, his resources overstretched, and his task, in the words of the Dictionary of National Biography, "perhaps the most ungracious duty that has ever fallen to the lot of a naval officer." According to his instructions, Graves was charged with supporting customs officials enforcing the various revenue and trade acts governing North American colonial trade within the empire, especially the Boston Port Act. With only 26 ships and over one-thousand miles of coastline from Nova Scotia to Florida to patrol, Graves's task was Sisyphean. Manning problems made the Royal Navy's problems even more acute, thus forcing it to resort to press gangs in order to supplement the ships' slender crews. Compounding the problem was the attitude and behavior of navy officers who did not recognize local authority and were more often contemptuous of local officials and sensitivities. Headquartered in Boston, Graves was at the center of the Revolutionary turmoil in New England. His sailors manned the boats that ferried British soldiers across the Charles Riveren route to Concordon the night of 18 April 1775. Two months later, on 17 June 1775, his sailors again helped ferry troops, this time to the Charlestown Peninsula, while several of his ships provided fire support for the pyrrhic victory at Bunker Hill. During the Siege of Boston, Admiral Graves, on 6 October 1775, ordered Lieutenant Henry Mowatt, commanding the armed vessel, to destroy seaports that were supporting the rebellion. Mowatt burned Falmouth on 18 October. On 27 January 1776, Vice Admiral Richard Howe succeeded Graves as commander-in-chief of the North American station. Graves returned to England without a command. In September 1777 he declined command of Plymouth, but indicated a desire to return to active duty. Graves advanced to admiral of the blue on 29 January 1778, admiral of the white on 8 April 1782, and died at his estate at Hembury Fort, Honiton, Devon on 8 March 1787. A monument sculpted by John Bacon but designed by a "Miss Burgess" was erected in Buckerell in Devon in the same year.