Although less well known today than her infamous sister-in-law, Lucrezia Borgia, Isabella d’Este was one of the most celebrated and influential women of the Renaissance. A powerful patron of the arts whose often aggressive acquisition policies defied contemporary expectations of her sex, she cultivated relationships with the leading writers, composers and artists of the time and became the first woman in Europe to develop a personalised gallery space with specially designed cabinets to display her vast collections. Admired throughout Europe for her style and taste, she was dubbed ‘the first lady of the world’ by the poet and playwright Niccolò da Corréggio.

Isabella was far more than just an elegant aristocrat with an enviable art collection. A skilled diplomat who gladly took on the reins of power when her husband, Francesco II Gonzaga, was away fighting, she made use of her network of spies and carefully cultivated friendships in order to charm conflicting factions during the tumultuous Italian Wars and secure Mantua’s survival. Her refined duplicity led later historians to refer to her as ‘Machiavelli in skirts’.

Daughter of the second Duke of Ferrara and Duchess Eleonora d’Aragona, she was fortunate to have parents who appreciated her intellect and gave her an exceptional humanist education. By the time she was 16 years old, Isabella could converse fluently in Greek and Latin, confidently discuss politics, and play multiple musical instruments.

At age six she had been betrothed to Gonzaga, Marquis of Mantua, a marriage that was intended to bring power, influence and security to the Estes, but also necessitated a delicate diplomatic balancing act from the outset due to shifting alliances during the tumultuous years of the Italian Wars. Francesco, her future husband, was for a time a mercenary commander with the Venetians, later fighting for the Franco-Papal imperial coalition against Venice, while Isabella had family ties to Venice’s enemies Ferrara and Milan, the latter via her younger sister Beatrice’s marriage to Ludovico Sforza, Duke of Milan.

Isabella proved more than equal to the task. While careful not to arouse opposition in an era that was wary of strong women, she skillfully projected an image of an elegant and refined patron of the arts in order to win influence and fame, and to develop a network of powerful friends that could aid the houses of Este and Gonzaga.

Once settled in her new position as Marchioness of Mantua, she set about creating a cultured, courtly environment similar to the one she had grown up with in Ferrara. Two rooms of her residence on the main floor of the Ducal Palace of San Giorgio were turned into a studiolo and a grotto, private spaces for writing, study and displaying what would become a vast and celebrated collection of art.

Andrea Mantegna, Pietro Perugino and Lorenzo Costa were just some of the illustrious names who helped turn her studiolo into a magnificent display of mythological, allegorical and religious scenes. However, she was a demanding patron who insisted on being heavily involved in the composition of works, even going so far as to choose the measurements of each piece, factors that led Giovanni Bellini to refuse a commission. And woe betide any artists who displeased her. Giovanni Luca Liombeni was threatened with imprisonment in the bridge dungeon if he did not finish his work quickly enough.

Isabella also used art to cultivate her image via portraits. Leonardo da Vinci created a preparatory drawing of her holding a book, while Titian painted her wearing her trademark zazara, an innovative turban-like headpiece made from a combination of real hair, fake hair, silk and gold threads, and decorated with jewels. Indeed, she became so deeply associated with the zazara that, over the years, several paintings of other women wearing it have been misattributed as portraits of Isabella.

Fashion was hugely important to her and she utilised her network of agents and diplomats to bring her the very best for her wardrobe – ostrich feathers, furs, silks, velvets, Reims linens and Ocalia gloves, but as Sarah Cockram has explained in her chapter on Isabella in the marvellously titled Sartorial Politics in Early Modern Europe, her passion for fashion was far from frivolous and was in fact an essential element of statecraft.

Her reputation as an arbiter of taste spread throughout Europe and enabled her to further cultivate her valuable network of contacts. The courts of France and Spain requested dolls dressed in replicas of her outfits in order to have them copied. Presenting gifts of her signature pieces could win favour among the many notable ladies eager to emulate her style. She sent bracelets perfumed with her own personal scent to Queen Claude of France, who wore them constantly, and later a pair of perfumed gloves, a strategy designed to win French support for the Duke of Urbino, Isabella’s son-in-law, against Medici threats.

Isabella’s ladies-in-waiting, known as the donzelle, were a key part of her fashionable machinations. Beautiful and finely dressed, they were used to attract powerful figures in order to push political agendas or extract information, allowing Isabella to use sex as a weapon without compromising her own virtue. Competition over the affection of one of her most celebrated donzelle, Eleonora Brognina, was engineered between the imperial ambassador Matteo Lange, Bishop of Gurk, and the viceroy of Naples, Ramon de Cardona, in order to persuade the infatuated gentlemen to further the Gonzaga cause.

When her brother Alfonso d’Este was betrothed to Lucrezia Borgia, a union to which Isabella was opposed, she sent spies to report back on Lucrezia’s style to make sure she was not upstaged at the wedding ceremony, knowing full well that she would be keenly observed by the Ferranese nobility and visiting dignitaries. Although she could not hope to compete with Lucrezia’s vast wealth and jewels, she chose to send out a subtle message by wearing an elegant gown embroidered with her personal emblem to greet her new sister-in-law. Formed of a musical clef matching the pitch of her voice and a pattern of rests in the shape of an M representing Marchesa, Mantua and Musica, it suggested cultural connoisseurship, female virtue, political acumen and self-control, and proclaimed Isabella’s refined nature in contrast to Lucrezia’s notoriety.

The wedding was a highly-charged political event and acts as an example of the careful diplomacy Isabella and Franceso practised throughout their marriage. Believing that Mantua might be at threat from Lucrezia’s brother, Cesare Borgia, Franceso did not attend. Isabella’s presence meant that offence was not caused and she could subtly push for Gonzaga advancement from the union.

As it turned out, Isabella was right to be wary of Lucrezia, as she later embarked on what, at the very least, was a romantic friendship, and may well have been a full-blown affair, with Francesco. However, despite her outward image of refinement, Isabella was not one to cross. She had shown her mettle early in the marriage when she had helped Francesco engineer the downfall of Francesco Secco, the lieutenant general of Mantua, whose authority thwarted her desire for co-rule, and she continued to be willing to get rid of anyone who stood in her way or opposed her. Although Lucrezia could obviously not be touched, the poet Ercole Strozzi, a favoured courtier of Francesco’s who was likely an intermediary between the couple, could be made an example of. On a June evening in 1508 his body was found on a street corner in Ferrara with 22 dagger wounds and his hair pulled out, a murder that Cockram believes was likely to have been carried out ‘with Isabella’s tacit approval, if not her active support’.

Despite the affair, just one of Francesco’s many throughout their marriage, Isabella campaigned passionately for her husband’s release after he was taken prisoner by the Venetians in 1509 while fighting for the Franco-Papal coalition against Venice in the War of the League of Cambrai. Drawing on the powerful connections she had forged throughout Europe and beyond, Isabella wrote to the pope, the cardinals Medici, Volterra, Sanseverino and Aragon, the queen of France, the Duke and Duchess of Bourbon and the Dukes of Saxony and Bavaria, as well as sending envoys to the King of Hungary and the Ottoman Sultan. At the same time, she sought to reassure her officials that she had ‘sufficient spirit to protect the state’, which indeed she did, keeping Mantua safe from its enemies and pseudo-protectors throughout her regency.

Francesco was eventually released in July 1510, when the pope abruptly turned on his erstwhile allies in the League of Cambrai and sided with the Venetians. It seems he was fearful that Isabella would cede strategically vital Mantuan territory to Ferrara and France, fears boosted by the whisperings of  Francesco’s advisor Ludovico (Vigo) di Camposampiero, whose loathing of Isabella was entirely mutual. Although Isabella had never had any such intentions, she was delighted that Vigo’s nefarious rumours had acted in her favour.

Isabella and Francesco’s relationship seems to have cooled towards the end of his life, in part because he seemed to favour advisors such as Vigo,  and she spent much of this time on diplomatic missions abroad. Given that Francesco was starting to suffer seriously from the syphilis he had contracted as early as 1496, she may also have been keen to avoid any intimate contact. However, despite an element of frostiness, Isabella was still called to his deathbed in March 1519 and named as regent for their eldest son Federico in his will.

She would be regent of Mantua until Federico reached his majority in 1521, during which time she rid herself of troublesome figures such as Vigo, who met a bloody end after he was unwise enough to spread more rumours about her in exile. Remaining at the heart of governance and culture until the end of her life, she continued to act as a valued advisor and promoter of her family’s interests.

Her enduring influence and the unwavering respect in which she was held was made abundantly clear during the Sack of Rome in 1527. Isabella was visiting the city when the mutinous troops of the Holy Roman Emperor Charles V embarked on their terrifying spree of violence and looting, which saw Pope Clement VII forced to take refuge in the fortress of Castel Sant’Angelo, but her residence was one of the few that was left unscathed. She was even able to shelter some 2,000 people within its walls. With her youngest son Ferrante fighting for the emperor and another son Ercole now a cardinal on the side of the papacy, she had ensured, as always, that all sides were covered.