 In April 1795 , the inshore squadron of the British blockade at Brest was commanded by Rear @-@ Admiral John Colpoys , who had at his command five ships of the line : HMS London , HMS Valiant , HMS Colossus , HMS Hannibal and HMS Robust and frigates HMS Astraea and HMS Thalia . Colpoys ' ships had formed an effective blockade : on 29 March they had taken the French corvette Jean Bart and the following day recaptured a lost British merchant ship . At 10 : 00 on 10 April , the British squadron was cruising off the approaches to Brest when three ships were spotted to the west . 
