Castilian ships had fought against England as the allies or mercenaries of France, and there had been instances of piratical violence between the trading ships of both nations. A Castilian merchant fleet was loading cargoes in the Flemish ports to be carried to the Basque coast. The ships were armed and had warships with them. They were all under the command of Don Carlos de la Cerda, a soldier of fortune who belonged to a branch of the Castilian royal family. On its way to Flanders the Castilian fleet had captured a number of English trading ships, and had thrown the crews overboard. Piratical violence and massacre of this kind was then common on the sea. On 10 August, when the king was at Rotherhithe, he announced his intention of attacking the Castilians on their way home. The rendezvou