 In November 1781 , the 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 HMS Victory . Kempenfelt was ordered to intercept the convoy , which he did in the afternoon of 12 December in the Bay of Biscay , approximately 150 miles ( 241 @.@ 4 km ) 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 . 
