HMS Agamemnon was a 64-gun third-rate ship of the line of the Royal Navy. She saw service in the American War of Independence and French Revolutionary and Napoleonic Wars and fought in many major naval battles. She is remembered as Horatio Nelson's favourite ship, and she was named after the mythical ancient Greek king Agamemnon, the first ship of the Royal Navy to bear the name.

The future Lord Nelson served as Agamemnon<nowiki/>'s captain from January 1793 for three years and three months, during which time she saw considerable service in the Mediterranean. After Nelson's departure, she was involved in the infamous 1797 mutinies at Spithead and the Nore, and in 1801, she was present at the first Battle of Copenhagen, but she ran aground before being able to enter the action.

Despite Nelson's fondness for the ship, she frequently needed repair and refitting and would likely have been hulked or scrapped in 1802 had the war with France not recommenced. She fought at the Battle of Trafalgar on 21 October 1805 as part of Nelson's weather column, where she forced the surrender of the Spanish four-decker Santísima Trinidad. Agamemnon<nowiki/>'s later career was served in South American waters off Brazil.

Her worn-out and poor condition contributed to her being wrecked when, in June 1809, she grounded on an uncharted shoal in the mouth of the River Plate whilst seeking shelter with the rest of her squadron from a storm. All hands and most of the ship's stores were saved, but the condition of the ship's timbers made it impossible to free the ship; her captain was cleared of responsibility for the ship's loss thanks to documents detailing her defects. In 1993, the wreck of Agamemnon was located, and several artefacts have since been recovered, including one of her cannons.

Construction

thumb|right|A model of Agamemnon at [[Bucklers Hard]]

Agamemnon was ordered from the commercial shipbuilder Henry Adams at his Bucklers Hard shipyard on the Beaulieu River on 5 February 1777 to be built to the lines of the , as designed by Sir Thomas Slade. Her keel was laid down in May. She was constructed using timber sourced from the surrounding New Forest. The total cost of her construction was £38,303 15s 4d. She was commissioned on 28 March 1781 under Captain Benjamin Caldwell—a full 13 days before her launch on 10 April.

A painting of the launch of Agamemnon by Harold Wyllie depicts blue skies and scores of spectators despite the Hampshire Chronicle describing the day as windy with heavy rain and with few spectators in attendance. and was the first Royal Navy vessel to bear the name. Lord Nelson regarded her as his favourite ship According to an article in The Gentleman's Magazine, her crew renamed her as they did not like the classical names that were in vogue at the Admiralty during this period (the crews of and also 'renamed' their ships to 'Billy Ruffian' and 'Polly Infamous' respectively, for the same reason).

American War of Independence

In November 1781, the British Admiralty had received intelligence that a large convoy was preparing to sail from Brest under Admiral de Guichen. The convoy was composed of transports carrying naval supplies for the West Indies and the French fleet in the East Indies. Agamemnon was part of Admiral Richard Kempenfelt's squadron of 18 ships (11 of which mounted 64 or more guns), which he commanded from . Kempenfelt was ordered to intercept the convoy, which he did in the afternoon of 12 December in the Bay of Biscay, approximately south-west of Ushant. With the French naval escort to leeward of the convoy, Kempenfelt attacked immediately, capturing 15 of the transports before nightfall. The rest of the convoy scattered, most returning to Brest; only five transports reached the West Indies.

Early in 1782, she sailed to the West Indies as part of Admiral Sir George Rodney's squadron, with Rear-Admiral Sir Samuel Hood as his second in command. On 9 April, the Battle of the Saintes began with an indecisive skirmish, in which the ships of the vanguard division, under Hood's command, were severely damaged and forced to withdraw to make repairs. On 12 April, Agamemnon took part in the second action, which proved much more decisive. During the battle, Agamemnon had two lieutenants and 14 crewmen killed, and 22 others were wounded. Later in the autumn, Agamemnon fought the inconclusive Action of 22 October 1793 against a French frigate squadron off Sardinia.

In April and May 1794, seamen from Agamemnon, led by Nelson, helped capture the Corsican town of Bastia. The French surrendered on 21 May after a 40-day siege. After this action, Agamemnon was forced to sail to Gibraltar to undergo urgent repairs. The ship became worn out after just 16 months at sea despite having undergone a fairly extensive refit before being recommissioned. Shortly after that, the inhabitants of Corsica declared themselves to be subjects of His Majesty King George III.

thumb|left|Agamemnon (left) battling [[French ship Ça Ira (1781)|Ça Ira on 13 March 1795. The frigates (left, background) and Vestale (right) are also visible.]]

Agamemnon, still with the Mediterranean fleet—now under Vice-Admiral William Hotham, who had superseded Hood in December 1794—participated in the Battle of Genoa when a French fleet, comprising 15 ships of the line, was sighted on 10 March 1795. Three days later, the French having shown no signs that they were willing to give battle, Admiral Hotham ordered a general chase. The French ship Ça Ira lost her fore and main topmasts when she ran into one of the other ships of the French fleet, Victoire, allowing to catch up with and engage her. Agamemnon and came up to assist soon after, and continued firing into the 80-gun French ship until the arrival of more French ships led to Admiral Hotham signalling for the British ships to retreat. Ça Ira was captured the following day, along with Censeur, which was towing her, by Captain and .

Nelson was promoted to Commodore on 11 March. Shortly thereafter, in the action of 31 May 1796, boats from Agamemnon and Nelson's squadron captured a small convoy of French vessels off the Franco-Italian coast, while suffering minimal casualties.

On 10 June 1796 Nelson transferred his pennant to , Captain John Samuel Smith replacing him as Agamemnons commander. Having been deemed in great need of repair, Agamemnon then returned to England.

On 18 March 1800, Agamemnon was damaged when she ran onto the Penmarks Rocks. She came into Falmouth on 25 March 1800. On her way to port she had encountered , which assisted her and accompanied her into port. With the assistance of the crews from two sloops, the guardship , and troops from Pendennis Castle at the pumps, the crew managed to stop the water level in the hold rising any further. Agamemnon made for Plymouth for repairs. Movement caused the leak to gain on the men at the pumps once more, and when she was off Penlee Point, Agamemnon fired a gun for assistance. When she reached Plymouth she was lashed to a sheer hulk to prevent her sinking.

In response to developments in the Baltic in 1801 that threatened to deprive Britain of much-needed naval supplies, Agamemnon was sent as part of a fleet under Admiral Sir Hyde Parker and Vice-Admiral Lord Nelson to attack the Danish at Copenhagen. On 2 April, Agamemnon was part of Nelson's division that fought the Battle of Copenhagen. Agamemnon was positioned second in the line after , and after passing down the Outer Channel, she grounded whilst attempting to round the southern tip of the Middle Ground shoal. While the battle raged around her Agamemnon, along with and , both of which had also run aground, flew signals of distress. The three stranded ships were eventually pulled off the Middle Ground in the night of 3 April. In misty conditions on 20 October, Agamemnon captured a large American merchant brig, which she then took in tow. Not long after, signalled to Agamemnon that she was sailing straight towards an enemy fleet of 30 ships—Villeneuve's fleet had left port.

On 21 October 1805 Agamemnon fought in the Battle of Trafalgar. Agamemnon was positioned eighth in Nelson's weather column, with ahead and astern. Once engaged, she was firing both batteries, eventually pounding the great Spanish four-decker Santísima Trinidad until that ship was dismasted and, with 216 of her complement dead, struck her colours. Before Berry could take possession of the prize, the enemy van division began bearing down on the British line, having previously been cut off from the battle by Nelson's line-breaking tactics. With Nelson already dying below decks on Victory, Captain of the Fleet Thomas Hardy ordered Agamemnon and several other ships to intercept them. Three of the enemy ships broke off and ran for Cádiz; after briefly engaging Intrépide the British ships moved to try to cut off the fleeing ships. Over the course of the battle, Agamemnon suffered just two fatalities, and eight men were wounded.

Following the battle, Agamemnon, despite taking on three feet of water in her hold each hour, took under tow to Gibraltar. After carrying out repairs, the ship rejoined Vice-Admiral Collingwood's squadron, which had resumed the blockade of Cádiz.

In 1807 Agamemnon was part of Admiral James Gambier's fleet sent to take control of the Danish fleet before it could fall into French hands. She participated in the second Battle of Copenhagen, and as in the first in 1801, ran aground. After the ships returned to Rio in January 1809, the ship was fully surveyed by the carpenter, who drew up an extensive list of her defects. While working her way between Gorriti Island and the shore, Agamemnon struck an uncharted shoal. Captain Jonas Rose attempted to use the ship's boats, together with the stream and kedge anchors, to pull the ship off, but to no avail. The ship had dropped anchor on the shoal just previously, and it was discovered that she had run onto it when she grounded, the anchor having pierced the hull. On 17 June, with the ship listing heavily to starboard, Agamemnons stores and all her crew were taken off by boats from other vessels in the squadron, and the following day Captain Rose and his officers left the ship.

The court-martial for the loss of Agamemnon was held at Rio de Janeiro on 22 July 1809, aboard . It was found that the ship might have been saved if she had not been in such poor general condition, and Captain Rose was honourably acquitted.

arrived on 4 August, and stayed with the transports Kingston and Neptune as they salvaged what could be salvaged from Agamemnon. Neptune left on 22 September, but Kingston and Nancy stayed as Kingston continued salvage efforts. On 16 November a gale came up and late the next day boats sent to the wreck reported that she was strewn in pieces all over the beach. On 28 November Nancy and Kingston departed together, but soon separated with Nancy sailing for Rio de Janeiro, which she reached on 15 December.

Legacy

In March 1993, the wreck was located north of Gorriti Island in Maldonado, Uruguay Bay Punta del Este by sonar operator Crayton Fenn. Sonar used was a Klien 595 system. Later in 1997, with the help of Mensun Bound documented the remains and recovered several artefacts, including a seal bearing the name 'Nelson,' and one of Agamemnons 24-pounder guns from her main gundeck.

The historical novelist Patrick O'Brian selected Agamemnon as one of the ships on which Jack Aubrey served as lieutenant before the events of Master and Commander, the first novel in his Aubrey–Maturin series.Agamemnon has also been the subject of paintings by the British artist Geoff Hunt, a former president of the Royal Society of Marine Artists.

To mark the bicentenary of the Battle of Trafalgar, in 2005, the Woodland Trust planted 33 woods named after Royal Navy ships that fought in the battle: one each for the 27 ships of the line and six others for the frigates and smaller support craft. Agamemnon wood was planted in November 2005 on the Beaulieu Estate in Hampshire, near where Agamemnon was constructed.

The Royal Navy adopted the name 'Agamemnon' for one of their Astute-class nuclear submarines, constructed in the UK. HMS Agamemnon was commissioned on 22 September 2025.

Agamemnon Channel in the Sunshine Coast region of British Columbia, at the mouth of Jervis Inlet between Nelson Island and the Sechelt Peninsula, was named for Agamemnon by Captain George Henry Richards of HMS Plumper in 1860.

Herman Melville chooses the Agamemnon for the origin of the old Dansker in his novella Billy Budd.

Historical fantasy novelist Natasha Pulley uses the Agamemnon as a significant setting in her alternate history novel The Kingdoms.

Agamemnon is the subject of a song by The Teacups, "Agamemnon"

Notes

a. Besides Agamemnon, the other engaged British ships were ,