In 1739 he was sent to fight against the Spanish in the Caribbean. He captured Porto Bello (now in Panama) in the opening phase of the War of Jenkins’s Ear in 1739, but failed disastrously at Cartagena (now in Colombia) in 1741. His boat-cloak of grogram (a mixture of silk, mohair, and wool) gave him the nickname “Old Grog”. “Grog” became the name of the naval rum ration when diluted with three parts of water, as Vernon was in the habit of issuing to his own sailors. He was removed from the active list in 1746 because he was thought to be the author of anonymous pamphlets attacking the Admiralty.