Ferdinand II of Aragón (1452-1516) and Isabella I of Castile

Ferdinand II of Aragón, surnamed the Catholic, was king of Aragón, Castile, Sicily from 1468, Naples from 1504, and finally of Navarra.

In 1459 he married Isabella I of Castile, and in 1474 they assumed joint rule of Castile. So they united their two kingdoms, running them as one country although officially separated. Granada fell into them in 1492 and the unification of Spain was thus accomplished. In the same year, in order to consolidate religious and political unity, they decided to expel all Jews who refused to accept Christianity. And few years later, in 1502, decided to expel the Moors But many Moors and a number of Jews pretended to accept Christianity and remained in Spain. The Catholic kings also instituted the Inquisition.

In 1492 Christopher Columbus undertook the voyage for the discovery of the new world under the auspices of Ferdinand the Catholic. Thus under Ferdinand II Spain became an Atlantic power, revolutionizing the commerce of Europe, searching for American gold and creating the Golden Century.

But Ferdinand was also interested in Mediterranean affairs. And thus he began Spain struggle with France for the control of Italy.His General Fernández de Córdoba conquered for him Naples in 1504. Ferdinand joined the League of Cambrai against Venice, and later the Holy League against France in 1511. The Holy League was an alliance formed by by Pope Julius II for the purpose of expelling Louis XII from Italy. The Vatican, Venice, the Swiss cantons, Ferdinad II of Aragon, Henry VIII of England and Holy Roman Emperor Maximilian I were the league's chief members.

Isabel died in 1504, and left her kingdom to her daughter Joanna. But by this time Joanna was quite insane and Ferdinad retained control over Castile for his daughter. First for a brief period, and then after the death of Joanna's ambitious husband Philip I (1506), until Ferdinad's own death in 1516. Holy Roman Emperor Charles V, Joanna's son, succeeded on the throne of Castile, and also succeeded Ferdinand the Aragonese throne. Thereafter the two thrones were united.

Some historians believe that Ferdinand was the inspiration for Niccolò Machiavelli's The Prince.