Jervis saw considerable action with the fleet off North America during the seven years’ war. He served under Sir Charles Saunders on the expedition against Quebec; was on friendly terms with Wolfe, and with Col. Barré with whom he was later connected politically. After intermittent service between the wars, Jervis became captain of the Foudroyant in 1775, but remained inactive till 1778 when he joined Keppel’s fleet, and took part in the action off Ushant. Sandwich in his list of ‘Officers of Admiral Keppel’s fleet’ drawn up in November 1778 wrote of him: ‘a good officer, but turbulent and busy, and violent as a politician attached to Mr. Keppel’.
In January 1783 he was returned for Launceston on the Duke of Northumberland’s interest at the request of Shelburne, a friend and correspondent of Jervis. Jervis voted for Pitt’s parliamentary reform proposals, 7 May 1783, and against Fox’s East India bill, 27 Nov. 1783. In Robinson’s list of January 1784 and in Stockdale’s list of 19 Mar. he was classed as ‘pro’. At the general election Jervis was returned for Great Yarmouth as an Administration candidate. He again voted for parliamentary reform, 18 Apr. 1785. He voted against Richmond’s fortifications plans, 27 Feb. 1786, which he had already opposed as a member of a commission of inquiry; but with Pitt over the Regency, 1788-9. Jervis’s infrequent speeches in the House were invariably connected with naval matters: that of 2 Mar. 1786, in which he exposed the inefficiency of naval maintenance and told the House of his ‘disposition ... to root up and totally prevent the growth of evils so enormous and alarming’,
After his death on 13 Mar. 1823, the Gentleman’s Magazine (1823, p. 371) wrote of him:
He was a man of strong and acute mind, resolute in what he undertook and unbending in his ideas of discipline and subordination. The British navy has been incessantly improving by those rules which he had prescribed for its management.