In 1512, the young king started a war in France. Although England was an ally of Spain, one of France's principal enemies, the war was mostly about Henry's desire for personal glory, despite his sister Mary being married to the French king Louis XII. The war accomplished little. The English army suffered badly from disease, and Henry was not even present at the one notable victory, the Battle of the Spurs. Meanwhile, James IV of Scotland (despite being Henry's other brother-in-law), activated his alliance with the French and declared war on England. While Henry was dallying in France, Catherine, who was serving as regent in his absence, and his advisers were left to deal with this threat. At the Battle of Flodden on 9 September 1513, the Scots were completely defeated. James and most of the Scottish nobles were killed. When Henry returned from France, he was given credit for the victory.