Philip's martial training was undertaken by his governor, Juan de Zúñiga, a Castilian nobleman who served as the "commendador mayor" of Castile. The practical lessons in warfare were overseen by the Duke of Alba during the Italian Wars. Philip was present at the Siege of Perpignan in 1542 but did not see action as the Spanish army under Alba decisively defeated the besieging French forces under the Dauphin of France. On his way back to Castile, Philip received the oath of allegiance of the Aragonese Cortes at Monzón. His political training had begun a year previously under his father, who had found his son studious, grave, and prudent beyond his years, and having decided to train and initiate him in the government of the Spanish kingdoms. The king-emperor's interactions with his son during his stay in Castile convinced him of Philip's precocity in statesmanship, so he determined to leave in his hands the regency of the Spanish kingdoms in 1543. Philip, who had previously been made the Duke of Milan in 1540, began governing the most extensive empire in the world at the young age of sixteen.