The Spanish conquest of the Iberian part of Navarre was initiated by Ferdinand II of Aragon and completed by his grandson and successor Charles V in a series of military campaigns lasting from 1512 to 1524. Ferdinand was both the king of Aragon and regent of Castile in 1512. When Pope Julius II declared a Holy League against France in late 1511, Navarre attempted 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 own Italian armies.

Ferdinand II was King of Aragon from 1479 until his death in 1516. As the husband of Queen Isabella I of Castile, he was also King of Castile from 1475 to 1504. He reigned jointly with Isabella over a dynastically unified Spain; together they are known as the Catholic Monarchs. Ferdinand is considered the de facto first king of Spain, and was described as such during his reign, even though, legally, Castile and Aragon remained two separate kingdoms until they were formally united by the Nueva Planta decrees issued between 1707 and 1716.