The 1469 marriage of Ferdinand (1452–1516) and Isabella (1451–1504) brought previously separate Spanish kingdoms (Aragon and Castile) under their joint control. Together the monarchs went on to rule Spain and expand their realm of influence until Isabella’s death in 1504. (Ferdinand ruled without his wife thereafter.) Theirs was a reign that seemed to have religion on its side: In 1496 Pope Alexander VI conferred upon each of them the title “Catholic,” as in, “Ferdinand the Catholic” and “Isabella the Catholic.” And for good reason, because the king’s and queen’s most well-known acts seemed to have been motivated by their beliefs.

It was Ferdinand and Isabella who in 1478 established the infamous Spanish Inquisition, a court that imprisoned or killed Catholics who were suspected of not following religious teachings. While the Inquisition was aimed at discovering and punishing Muslims and Jews who had converted to Catholicism but who were thought to be insincere, soon all Spaniards came to fear its power. In 1482 the monarchs undertook a war with the (Muslim) Moors, conquering the last Moorish stronghold at Granada in 1492, and forcing them back to Africa after four centuries of occupation—and influence—in the Iberian Peninsula (Spain and Portugal). The recovery of Iberia had been motivated by religion; when the king and queen expelled the Moors, they also believed they were expelling Islam from their kingdom.

That year, 1492, was a fateful one for the Spanish: Not only were the Moors driven out, but Ferdinand and Isabella also turned their attention to the Jewish “threat,” expelling them, too. (Those who remained went underground with their faith; those Iberian Jews who migrated spread their division of Judaism, called Sephardim, to North Africa and the Middle East.)

Most students of history know 1492 best as the year that explorer Christopher Columbus (1451–1506) sailed to the New World. It was Ferdinand and Isabella who sponsored his voyage, believing that the conquered lands would not only add to their authority but would provide new territory for the spread of Catholicism. The Spaniards soon emerged as a formidable sea power in the Atlantic.

For all their fervor, Isabella and Ferdinand were also interested in education and the arts, and they sponsored advances in both areas during their reign. Their legacy included their grandson Charles V (1500–1558), who, through marriage, became Holy Roman Emperor and ruled from 1519 to 1558 as one of the all-powerful Habsburgs.