Unlike the Muslims of Granada, who were under Muslim rule until 1492, Muslims in the rest of Castile had lived under Christian rule for generations. Following the conversions in Granada, Isabella decided to impose a conversion-or-expulsion decree against the Muslims. Castile outlawed Islam in a legislation dated July 1501 in Granada, but it was not immediately made public. The proclamation took place on February 12, 1502, in Seville, and then locally in other towns. The edict affected “all kingdoms and lordships of Castile and Leon“. According to the edict, all Muslim males aged 14 or more, or females aged 12 or more, should convert or leave Castile by the end of April 1502. The edict justified the decision by saying that after the successful conversion of Granada, allowing Muslims in the rest of Castile would be scandalous, even though it acknowledged that these Muslims were peaceful. The edict also argued that the decision was needed to protect those who accepted conversion from the influence of the non-converted Muslims.
On paper, the edict ordered expulsion rather than a forced conversion, but it forbade nearly all possible destinations; in reality, the Castilian authorities preferred Muslims to convert than emigrate. Castile’s western neighbor Portugal had already banned Muslims since 1497. The order explicitly forbade going to other neighboring regions, such as the Kingdoms of Aragon and Valencia, the Principality of Catalonia, and the Kingdom of Navarre. Of possible overseas destination, North Africa and territories of the Ottoman Empire were also ruled out. The edict allowed travel to Egypt, then ruled by the Mamluk Sultanate, but there were few ships sailing between Castile and Egypt in those days. It designated Biscay in the Basque country as the only port where the Muslims could depart, which meant that those from the south (such as Andalusia) would have to travel the entire length of the peninsula. The edict also set the end of April 1502 as the deadline, after which Islam would become outlawed and those harboring Muslims would be punished severely. A further edict issued on September 17, 1502, forbade the newly converted Muslims to leave Castile within the next two years.
Meanwhile, Navarre’s queen Catherine de Foix and her co-ruling husband John III had no interest in pursuing expulsion or forced conversions. When the Spanish Inquisition arrived in Navarre in the late fifteenth century and began harassing local Muslims, the Navarran royal court warned it to cease.
However, in 1512, Navarre was invaded by Castile and Aragon. The Spanish forces led by King Ferdinand quickly occupied the Iberian half of the kingdom, including the capital Pamplona; in 1513, he was proclaimed King. In 1515, Navarre was formally annexed by the Crown of Castile as one of its kingdoms. With this conquest, the edict of conversion came into effect in Navarre, and the Inquisition was tasked with enforcing it.
Despite presiding over the conversions of Muslims in his wife’s Castilian lands, Ferdinand II did not extend the conversions to his Aragonese subject. Kings of Aragon, including Ferdinand, were required to swear an oath of coronation to not forcibly convert their Muslim subjects. He repeated the same oath to his Cortes (assembly of estates) in 1510, and throughout his life he was unwilling to break it. Ferdinand died in 1516, and was succeeded by his grandson Charles V, who also swore the same oath at his coronation.
Shortly after the Revolt of the Brotherhoods during the 1520s and its anti-muslim sentiment, Charles tried to release himself from the oath he swore to protect the Muslims. He wrote to Pope Clement VII in 1523 and again in 1524 for this dispensation. Clement initially resisted the request, but issued in May 1524 a papal brief releasing Charles from the oath and absolving him from all perjuries that might arise from breaking it.
On November 25, 1525, Charles issued an edict ordering the expulsion or conversion of remaining Muslims in the Crown of Aragon. Similar to the case in Castile, even though the option of exile was available on paper, in practice it was almost impossible.
A very small number of Muslims managed to escape to France and from there to the Muslim North Africa. Some revolted against this order. The crown’s troops defeated this rebellion in a campaign which included the killing of 5,000 Muslims. After the defeat of the rebellions, the entire Crown of Aragon was now nominally converted to Christianity. Mosques were demolished, first names and family names were changed, and the religious practice of Islam was driven underground.