Sighted by British frigate HMS Naiad enforcing the blockade of Vigo late on the 15 October, the Spanish ships were in the last stages of their journey.

Vast quantities of gold, silver and valuable trade goods crossed the Atlantic in regular armed frigate convoys.

[8] At 03:30 on 16 October, another sail was spotted to the southwest, rapidly revealed to be a second British frigate, the 38-gun HMS Ethalion under Captain James Young.

[10] As Naiad, Triton and Alcmene streamed past in pursuit of Santa Brigida, Young focused his attention on Thetis, coming within range at 11:30.

Pillon was an experienced officer with a good knowledge of the Northern Spanish coast and he intended to lose his pursuers in the rocky channels of Cape Finisterre.

Captain Gore on Triton, which was in full flow at seven knots, was unaware of the obstacle and at 05:00 crashed into them, coming to a juddering halt and inflicting severe damage to his ship's hull.

Gore was able however to bring Triton off soon afterwards and continued pursuit, assisted by Digby on Alcmene who was able to block Pillon's route into Porte de Vidre.

[6] Both frigates opened fire on Santa Brigida at 07:00 as the Spanish ship sought shelter in the rocks at Commarurto close to the safe harbour at Muros, Pillon's movement hampered by the coastal rias that blocked the wind.

[11] They then sailed directly for the fleet base at Plymouth, arriving on 22 October to find that Thetis and Ethalion had reached the port the day before.

[6] In the aftermath, the sailors of the squadron were noted in the streets of Portsmouth wearing "bank notes stuck in their hats, buying watches for the fun of frying them, and issuing laws that any of their crew who appeared without a gold-laced hat should be cobbed, so that the unlucky man who appeared in silver could only escape by representing that the costlier articles were all bought up, but he had compelled the shopkeeper to take money for gold lace.

[14] The sums awarded as prize money, distributed in equal proscribed shares among the crews of Ethalion, Naiad, Alcmene and Triton were among the largest ever recorded.

[23] On the only subsequent occasion when a Spanish treasure fleet was successfully intercepted, at the Battle of Cape Santa Maria in October 1804, an even greater haul was captured.