Spanish conquest of the Iberian part of Navarre was commenced by Ferdinand II of Aragon and completed by Charles V in a series of military campaigns extending from 1512 to 1524, while the war lasted until 1528 in the Navarre to the north of the Pyrenees. Ferdinand the Catholic was in 1512 both king of Aragon and regent of Castile. When Pope Julius II declared a Holy League against France in late 1511, Navarre tried to remain neutral. Ferdinand used this as an excuse to attack Navarre, conquering it while its potential protector France was beset by England, Venice, and Ferdinand's Italian armies. Several attempts were made to reconquer Iberian Navarre starting right after the Castilian invasion , notably a halfhearted reconquest attempt in 1516 and a fully-fledged French-Navarrese reconquest campaign in 1521. All were defeated by the Spanish, and clashes came to halt to the north of the Pyrenees in 1528, when the Spanish troops withdrew from Lower Navarre. The Treaty of Cambrai between Spain and France in 1529 sealed the division of Navarre along the Pyrenees, while the independent Kingdom of Navarre survived in Lower Navarre ruled by the lineage of the Albrets united to their principality of Béarn, showing close links with France. The kingdom was absorbed into France in 1620 .. From what year to what year were the operations of war conducted?