Fénix was an 80-gun ship of the line (navio) of the Spanish Navy, built by Pedro de Torres at Havana in accordance with the system laid down by Antonio Gaztaneta launched in 1749. In 1759, she was sent to bring the new king, Carlos III, from Naples to Barcelona. When Spain entered the American Revolutionary War in June 1779, Fénix set sail for the English Channel where she was to join a Franco-Spanish fleet of more than 60 ships of the line under Lieutenant General Luis de Córdova y Córdova. The Armada of 1779 was an invasion force of 40,000 troops with orders to capture the British naval base at Portsmouth.

The Battle of Cape St. Vincent was a naval battle that took place off the southern coast of Portugal on 16 January 1780 during the American Revolutionary War. A British fleet under Admiral Sir George Rodney defeated a Spanish squadron under Don Juan de Lángara. The battle is sometimes referred to as the Moonlight Battle because it was unusual for naval battles in the Age of Sail to take place at night. It was also the first major naval victory for the British over their European enemies in the war and proved the value of copper-sheathing the hulls of warships.