On 21 October 1805, under the command of Captain Richard King, Achille was in Admiral Collingwood's column at the Battle of Trafalgar, seventh in the line, between Colossus and Revenge.

[2] Achille opened fire on the rear of the French and Spanish fleet at 12.15, engaging the 74-gun Montanes, for fifteen minutes, before sailing on to meet Argonauta of 80 guns, which had already been battling with other British ships.

After exchanging broadsides, the French ship sailed on and was replaced on the starboard side by the 74-gun French ship Berwick, and for the next hour and a quarter she lay close alongside Achille, receiving a pounding that eventually forced Berwick to surrender with over 250 casualties – almost half her crew.

Achille suffered 13 killed and 59 wounded in the battle, in stark comparison to the heavy losses she inflicted on her French and Spanish adversaries.

[Note 2] On 17 July 1812, boats from Achille and Cerberus captured or destroyed 12 enemy trabaccolos off Venice.