The conquest of various American territories made Spain the leading European power of the 16th century, leading to continuous conflict with France and the emerging power of England. In addition, the deeply religious monarchs Charles V and Philip II saw a role for themselves as protectors of the Catholic faith against Islam in the Mediterranean, and against Protestantism in northern Europe. This meant the Spanish Empire was almost continuously at war. Of all these conflicts, the Eighty Years' War was the most prolonged and had a major effect on the Spanish finances and the morale of the Spanish people, who saw taxes increase and soldiers not returning, with little successes to balance the scales. The Spanish government had to declare several bankruptcies. The Spanish population increasingly questioned the necessity of the war in the Netherlands. The loss of Portugal in 1640 and the Peace of Westphalia in 1648, ending the war, were the first signs that the role of the Spanish Empire in Europe was declining.