Guipuzcoano was sailing as the flagship of an escort for a merchant convoy of the company, when they ran into a large British fleet under Admiral Sir George Rodney, bound for the relief of Gibraltar.

In a short action Rodney captured the entirety of the convoy and all its escorts, including the Guipuscoano, which he manned and named in honour of Prince William, sending her back to Britain with some of the merchants.

[1] On 8 January 1780 the convoy encountered a large British fleet off Cape Finisterre under Admiral Sir George Rodney, bound for the relief of Gibraltar.

[4] She was commissioned under her first commander, Captain Stair Douglas, in April that year, and joined the Channel Fleet under Sir George Darby.

[4] Prince William then left the West Indies at the end of the year, sailing to North America and arriving there in October.

After some time spent laid up, she was fitted as a sheer hulk at Portsmouth between December 1790 and April 1791, and in this state saw out most of the French Revolutionary and Napoleonic Wars.

^ Rodney successfully relieved Gibraltar, and then engaged and defeated a Spanish fleet under Juan de Lángara at the Battle of Cape St Vincent, on 16 January 1780.