c1750- 82. He was of Irish descent.
Peacock was commissioned lieutenant on 12 June 1776, and in 1777 was serving on the Leeward Islands station aboard the Beaver 14, Commander James Jones, being present at her capture of the American privateer Oliver Cromwell 24 on 19 May off St. Lucia. In August he was appointed by the commander-in-chief, Vice-Admiral James Young, to his flagship, the Portland 50, Captain Thomas Dumaresq, and by the following spring had become her first lieutenant.
In March 1778 Peacock was appointed commander of the sloop Comet 10 which he brought back to England with a convoy to arrive at Deal on 8 July, being promoted master and commander with seniority from 22 July.
From the beginning of September 1778 he had the newly commissioned Childers 10, commanding her initially at Deal before taking her out on a short cruise in December, and then going out on another cruise from which he entered Portsmouth in early March 1779. At the end of the month he was sent out to Spain, Portugal and Gibraltar with the trade in the company of the Chatham 50, Captain William Allen, and Thetis 32, Captain John Gill, and after arriving at Gibraltar on 26 April he remained on that station. In June the Childers chased an American privateer into the midst of the Spanish fleet which had come out of Cadiz, but which made no attempt to prevent Peacock making his capture, and during the following month, by which time Spain had declared war on Britain, he destroyed a settee under the batteries of Ceuta.
On 27 January 1780 Peacock was posted captain of the Princesa 70 by Admiral Sir George Brydges Rodney, which ship had been captured at the Moonlight Battle off Cape St. Vincent on 16 January. On 9 October he was appointed to the frigate Carysfort 28, and after reaching Spithead from the Downs with a convoy at the end of the month he sailed from Portsmouth at the beginning of December in the company of the Chatham 50, Captain John Orde, conveying several vessels to the Carolinas and New York. Off Cape Cod on 5 October 1781, and whilst returning to New York from Halifax, he captured a large French vessel carrying masts to their Caribbean base at Cap François.
In October 1782 Peacock was appointed to the captured French frigate Aigle 40, which had been taken by Captain Hon. George Keith Elphinstone’s squadron on 15 September, but whilst conducting Captain Horatio Nelson on a tour of his new command he suffered a stroke. This was apparently not his first attack of apoplexy, and he died at New York on 13 December.
Peacock was well respected by his fellow officers.