On 04 Jun 1744 Lieutenant John Stanhope was promoted commander, joining the sloop Raven 14 which he commanded in the Mediterranean before sailing for North America in July 1775. Arriving with despatches at Boston in October, he served off Georgia in the following year, was present at the occupation of New York in July, and served in the expedition up the Hudson River to attack two rebel forts in the second half of 1777. On returning to England from the West Indies later that year he captured the American ship Vengeance and took her into Gibraltar. He paid the Raven off in November 1778.

On 15 Oct 1762 Rear-Admiral John Stanhope (age 18) was commissioned Lieutenant.

On 05 Mar 1779 Commander John Stanhope (age 34) was posted captain, joining the Garland 24 he commanded her in the North Sea that year as well as undertaking convoy duty to and from Newfoundland.

Around Jun 1780 Captain John Stanhope (age 35) he had the Pegasus 28 in which he went out to the Leeward Islands in January 1781, and after participating in the defence of St. Lucia against the French fleet in May he helped put down a mutiny aboard the Santa Monica 36, Captain John Linzee, on 16 July at English Harbour, Antigua.

On 25 Sep 1781 Captain John Stanhope (age 37) assisted the Cormorant 12, Commander James Kempthorne, in the capture of the American privateer Deane 16 off Long Island, and then returning to the Leeward Islands he was at the Battle of St. Kitts on 25-26 January 1782, and at the Battle of the Saintes on 12 April, although his vessel was not engaged. The Pegasus was paid off in the spring of 1783.

In 1790 Captain John Stanhope (age 45) commanded the frigate Arethusa 38 in 1790 for the Spanish Armament, but during the peace was not otherwise employed.

In Feb 1793 Captain John Stanhope (age 48) recommissioned the Vanguard 74 in February 1793 following the commencement of the French Revolutionary War and participated in the chase of Rear-Admiral Pierre Jean Vanstabel s squadron during the Channel fleet cruise of October-December, as well as in the capture by several vessels of the French corvette Blonde on 27 November. The Vanguard took a convoy out to the Leeward Islands from March 1794 to arrive at Barbados on 1 May, and Stanhope was succeeded by Captain Charles Sawyer twelve days later.

On 01 Jul 1795 Captain John Stanhope (age 50) was promoted a Rear-Admiral.

On 14 Feb 1799 Captain John Stanhope (age 54) was promoted a Vice-Admiral