natural son of Pope Alexander VI. He was a Renaissance captain who, as holder of the offices of duke of the Romagna and captain general of the armies of the church, enhanced the political power of his father's papacy and tried to establish his own principality in central Italy. His policies led Machiavelli (Machiavelli, Niccolò) to cite him as an example of the new “Prince.”

Cesare Borgia was the son of his father's most famous mistress, Vannozza Catanei. His father, at that time Cardinal Rodrigo Borgia, was vice chancellor of the church and had had three earlier children by other mistresses. Cesare was, however, the oldest of the four children born to Vannozza and Rodrigo (the others being Juan, Lucrezia, and Jofré) and was Rodrigo's second son. As was customary for second sons he was educated for a career in the church and in 1480 was dispensed from the slur of illegitimacy by Pope Sixtus IV so that he might hold ecclesiastical offices.

Although he was born in Italy and spent most of his life there, Cesare's family and cultural background was almost entirely Spanish. His elder half brother, Pedro Luis, was duke of Gandía, and all of his early benefices were in Spain. At the age of seven Cesare was made an apostolic prothonotary and canon of the cathedral of Valencia.

His early tutors were Paolo Pompilio and Giovanni Vera, both Catalans, and he was recognized as being exceptionally brilliant, as well as being, according to at least one observer, “the handsomest man in Italy.” In 1489 he went to the University of Perugia to study law and then passed on to the University of Pisa, where he studied under the famous jurist Filippo Decio and gained a degree in canon and civil law. In 1491 he became bishop of Pamplona, and in 1492, after the accession of his father to the papal throne, he was made archbishop of Valencia.

The election of his father as pope in 1492 changed the fortunes of Cesare Borgia. Besides becoming an archbishop, he was also made a cardinal in 1493, with the titular church of Sta. Maria Nova; he was now one of his father's principal advisers. It was already clear, however, that he did not have a true religious vocation; he was better known at the papal court for his hunting parties, his amorous liaisons, and his magnificent clothes than for the meticulous observance of his ecclesiastical duties.

On the death of Pedro Luis in 1488 the title of duke of Gandía had by-passed him and gone to his younger brother Juan, and it was he who was made commander of the papal army in 1496 for the first of Alexander's campaigns against his rebellious nobility, the Orsini. Cesare was reputed to have been extremely jealous of his brother, and when Juan was mysteriously murdered in 1497 the rumour gradually spread that Cesare was the culprit. There is, however, no evidence that Cesare murdered his brother (who had many other enemies) beyond the fact that he was certainly capable of murder, as he subsequently proved.

After the death of Juan, Cesare's martial and political leanings and his father's need for a trustworthy secular lieutenant coincided, and in 1498 Cesare gave up his cardinalate. Plans were laid for an important dynastic marriage for him, and, after an abortive attempt to win the hand of Carlotta, daughter of the King of Naples, he travelled to France to marry Charlotte d'Albret, sister of the King of Navarre. At the same time he received from Louis XII, the French king, the title of duke of Valentinois, and from this title he derived his nickname—Il Valentino.

The French marriage of Cesare ensured for him and his father French assistance in their plans to reestablish control in the Papal States and, if possible, to carve out a permanent Borgia state in Italy for Cesare. In 1499 Cesare, as captain general of the papal army, assisted by a large contingent of French troops, began a systematic occupation of the cities of Romagna and the Marches, which had largely fallen under the control of semi-independent papal vicars.

The campaign of 1499 saw the conquest of Imola and Forlì; that of 1500–01 brought Rimini, Pesaro, and Faenza into Cesare's hands; finally, in 1502, he captured Urbino, Camerino, and Senigallia. It was in this last campaign that Machiavelli, as one of the Florentine ambassadors attached to Cesare's camp, was able to observe at first hand the methods of the man who was to figure so largely in his later writings.

The activities of Alexander and Cesare, although they conformed very much to a pattern established by earlier 15th-century popes, aroused immense opposition within the Papal States and from the other Italian states. The propaganda war waged against them was vitriolic and lastingly effective. Cesare was portrayed as a monster of lust and cruelty who had gained an unnatural ascendancy over his father after having supposedly killed his brother, the favourite son, Juan. It seems likely, however, that the two Borgias worked very much in harmony; Alexander was by far the more astute politician, and Cesare the more ruthless man of action. Ambitious and arrogant, he was determined to establish himself as an Italian prince before his father died and left him deprived of the political and financial support of the papacy. Aut Caesar, aut nihil (“Either Caesar or Nothing”) was the motto he adopted to indicate the single-mindedness of his purpose. A number of political assassinations have been attributed to him, but the crime of which he was most clearly the author was the murder in August 1500 of his brother-in-law Alfonso (Alfonso I), duke of Bisceglie, the second husband of Lucrezia. It seems likely that this was an act of personal vengeance rather than a politically motivated assassination, but it contributed greatly to the fear and loathing in which Cesare was held.

The best example of Cesare's methods was his third Romagna campaign (1502–03). He opened with a lightning march on unsuspecting Urbino, which surrendered without a shot being fired. He then turned on Camerino, which was also quickly subdued. At this stage his leading commanders, fearing his power, turned against him in the so-called Magione conspiracy. Cesare, stripped of most of his troops, was forced to fight defensively in the Romagna. With lavish use of papal funds, however, he managed to rebuild his army while at the same time working on the diplomatic front to break up the league of the conspirators. Having succeeded in breaking it up, he arranged a rendezvous for reconciliation with some of the conspirators at Senigallia and, having isolated them from their troops, he then arrested and executed them (December 1502).

Cesare, with a powerful army he could trust, now seemed to be at the zenith of his fortunes. It is probable that he was planning an attack on Tuscany, which would have provided him with the independent state he craved, when his father died on Aug. 18, 1503. He himself was also ill at the time, and this circumstance, together with the subsequent election of a bitter enemy of the Borgias, Giuliano della Rovere, as Pope Julius II, lessened his already slim chances of survival. Julius refused to confirm Cesare as duke of the Romagna or captain general of the church and demanded the restoration of the Romagna cities. Cesare was arrested, won a brief respite by agreeing to surrender his cities, and fled to Naples only to be arrested once more by Gonzalo de Córdoba, the Spanish viceroy, who refused to join him in a league against the Pope. Cesare was then taken to Spain and imprisoned, first in the castle of Chinchilla near Valencia, and then at Medina del Campo, from whence he escaped in 1506. Unable to see any immediate prospect of returning to Italy, he took service with his brother-in-law, the King of Navarre, and was killed in 1507 in a skirmish with Navarrese rebels outside Viana. He was buried in the church of Sta. Maria in Viana.

Cesare Borgia was a man of extraordinary contrasts. Machiavelli found that he could be at times secretive and taciturn, at others loquacious and boastful. He alternated bursts of demonic activity, when he stayed up all night receiving and dispatching messengers, with moments of unaccountable sloth, when he remained in bed refusing to see anyone. He was quick to take offense and rather remote from his immediate entourage and yet very open with his subjects, loving to join in local sports and to cut a dashing figure.

There can be no doubt of the impact that he made in the Italy of his own day, but this impression was largely because of the backing he received from papal money and French arms. He was undoubtedly a master of politico-military manoeuvre, and it was a combination of daring and duplicity that brought him his striking successes and made him feared all over Italy. His abilities as a soldier and an administrator, however, were never really tested. He fought no major battles in his short military career, but this was perhaps a measure of his success as a planner. He had little time for the organization of the government of his Romagna duchy, but there are indications that he had plans for centralized government and bureaucratic efficiency, which to some extent justify the claims made for him as an administrator by Machiavelli. His interests tended to be scientific and literary rather than artistic, but once again time was too short for him to emerge as an important Renaissance patron. Leonardo da Vinci was for a short time his inspector of fortresses but executed no artistic commissions for him.

Machiavelli's apparent admiration for a man who was so widely feared and abhorred has led many critics to regard his portrayal of Cesare as an idealization. This interpretation, however, is not really the case. Machiavelli was well aware of the failings and limitations of Cesare Borgia, but he saw in him some of the qualities that he considered essential for the man who aspired to be a prince. The aggressiveness, the speed and ruthlessness of planning and execution, the opportunism of Cesare all delighted Machiavelli, who saw far too little of these qualities in the Italy of his day. Machiavelli was not attempting a rounded portrait of Cesare's character and qualities, which baffled him as much as they did most of his contemporaries.