Revolutionary Wars In August 1796 she was the flagship of Commodore
Horatio Nelson. In 1798 she was converted to serve as a
troopship. In 1800 under the command of Post Captain Sir Thomas Livingstone she was employed in the expedition to
Quiberon and
Belle Île under Sir
Edward Pellew, subsequently she was employed in the expedition to
Cádiz under Admiral
Lord Keith. Given that
Diadem served in the navy's
Egyptian campaign between 8 March 1801 and 2 September, her officers and crew qualified for the clasp "Egypt" to the
Naval General Service Medal (1847) that the
Admiralty authorised in 1850 to all surviving claimants.
Napoleonic Wars Between April and July 1810
Diadem was at Chatham being fitted for service as a troopship of 28 guns. In June 1810 Captain
John Phillimore (or Philmore) commissioned her for Lisbon. In January 1812 she carried released Danish prisoners of war from Plymouth to Chatham. Midshipman Drew's biography recollects that
Diadem, under the command of the squadron of
Home Riggs Popham, was employed on operations on the north coast of Spain, actively working with the Spanish insurgent forces. On 6 June 1812, the 1st Royal Marine Battalion embarked aboard
Diadem at Portsmouth. The battalion arrived off the coast near
Santoña on 15 June, and was involved in the attack on the fort at
Castro Urdiales. The fort's garrison of two companies of infantry capitulated on 8 July, the French having evacuated the town the day before. On 10 July, the battalion re-embarked, intending to go to
Portugalete, but returned to Castro shortly afterwards. Further reinforcements for the 2nd Royal Marine Battalion disembarked soon after
Diadem arrived on 29 November at Santander, On 21 December 1812,
Diadem embarked half of the 2nd Royal Marine Battalion from Santander, arriving in
Cawsand Bay on 4 January.
War of 1812 The American vessel was in the Bay of Biscay, near
Santander when on 7 October 1812 she encountered a British naval squadron, which captured her. The report of her capture noted that she was carrying coffee, sugar, and hides. ''Lloyd's List
reported that she had arrived at Portsmouth on 1 November. It also reported that she was a prize to Diadem''. On 30 March 1813, the
Diadem and the
Diomede embarked the
1st Royal Marine Battalion under the command of Major
Richard Williams. They arrived in Bermuda on 29 May 1813. Later, she sailed to the Halifax station. In June 1814, in company with the Leopard, and Diomede, with troops for Quebec. On 9 December 1814 she arrived at Falmouth, latterly from the Chesapeake.
Fate In February 1815, it was reported the
Diadem was to be paid off, being in a bad state. In May, work began at Chatham on being refitted as a Unrated Receiving Ship, this was completed in June.
Diadem was broken up in September 1832. ==Notes==