Empire of Blue Water: Henry Morgan and the Pirates Who Ruled the Caribbean Waves, by Stephan Talty; Simon & Schuster, 2008, $24.95. In 1654, a man called Thomas Gage travelled to Portsmouth to step aboard the Fagons, a ship on a mission from God. This renegade Dominican turned informer had, in his Catholic days, spent twelve years in the West Indies as a missionary, and had written a best-seller based on his experiences which persuaded Oliver Cromwell to take on the Spanish in the New World. Gage convinced the Lord Protector that the Pope’s plans for universal domination could…