In 1217, Prince Louis of France (the future Louis VIII, son of Philip August and father of Saint Louis) waged war in England hoping to seize the crown. The convoy bringing him much needed reinforcements was intercepted at sea, somewhere between Dover, Sandwich and South Foreland, and never reached the English coast. This naval battle is memorable in more ways than one. First of all, by its seniority, because it was one of the first Franco-English clashes at sea. By the tactical skill of the English, very innovative for the time. By the unusual personality of the French commander, Eustache Le Moine, a former monk turned pirate and warlord, who put his sword at the service of the highest bidder. Guy Le Moing, a specialist in medieval maritime history, brings it to life here, drawn from the best sources of medieval chronicles.