Henry's policy was rendered difficult by the incurable perverseness of the emperor and his son, the Duke Philip, but he managed to keep out of war with them, and even obtained from them the "Great Intercourse," a commercial treaty with the Low Countries which was of much use to England, as it provided for the free entry of English goods into Flanders, and of Flemish goods into England, and stipulated that the king and the duke should join together to put down piracy in the Narrow Seas. Some years later Henry was enabled to wring some further advantages out of Duke Philip, in a not very honourable way. The duke was sailing to Spain, when his ship was driven into Weymouth by a storm. The king made him welcome and entertained him royally, but would not suffer him to depart till he had promised to surrender the Yorkist refugee, Edmund de la Pole,[30] who was then staying in Flanders, and to still further extend the terms of the "Great Intercourse" to the benefit of English merchants (1506). [Sidenote: =Marriage of the Prince of Wales to Catherine of Aragon.=] With Ferdinand of Aragon, the astute and unscrupulous King of Spain, Henry was able to get on better terms than with his capricious neighbour in Flanders, since both were guided purely by self-interest. The two wily kings understood and respected each other, and resolved to ally themselves by a marriage. Accordingly Arthur, Prince of Wales, Henry's eldest son, was wedded to Catherine, the younger daughter of Ferdinand and Isabella. They were both mere children, and the prince died before he had reached the age of seventeen. But Ferdinand resolved that the alliance should not drop through, and the Princess Catherine was passed on to Henry, Arthur's younger brother and successor in the title of Prince of Wales. He was some years younger than his bride, and the marriage, as we shall presently see, was a most unhappy one. With his son's wife the English king received a large but unpunctually paid dowry. [Sidenote: =Scotland and Ireland.=]