Rear-Admiral John Leveson-Gower was a Royal Navy officer and politician from the Leveson-Gower family. As a junior officer he saw action at the Battle of Lagos in August 1759 during the Seven Years' War. As captain of HMS Valiant he was present at the Battle of Ushant on 17 July 1778 during the American War of Independence. He went on to be a junior Lord of the Admiralty and then First Naval Lord. He also sat as Member of Parliament for several constituencies.

The Battle of Ushant took place on 27 July 1778, and was fought during the American Revolutionary War between French and British fleets 100 miles (160 km) west of Ushant, an island at the mouth of the English Channel off the westernmost point of France. "Ushant" is the anglicised pronunciation of "Ouessant".