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.

Admiral George Brydges Rodney, 1st Baron Rodney, KB, was a British naval officer. He is best known for his commands in the American War of Independence, particularly his victory over the French at the Battle of the Saintes in 1782. It is often claimed that he was the commander to have pioneered the tactic of breaking the line.