When her mother returned to Ferrara, Isabella accompanied her, while the other two children remained in Naples for many years: Beatrice was adopted by her grandfather, and her little brother Ferrante was left under the tutelage of their uncle Alfonso.

[11] Prior to the magnificent banquet which followed the wedding ceremony, Isabella rode through the main streets of Ferrara astride a horse draped in gems and gold.

[14] On 11 February, speaking to her about the amusements he had with Beatrice, he wrote to her: "I will also strive to improve in order to give greater pleasure to the S. V., when I come for her this summer", and lamented the lack of "his sweet company".

[16] Despite the affection, Isabella began to feel envy for her sister Beatrice, first for the very fortunate marriage that had touched her and for the enormous riches, then for the two sons in perfect health who were born to her a short time later, while she seemed unable to have children,[17][18] and in this aroused the concerns of her mother Eleonora, who continually exhorted her in letters to be as close as possible to her husband.

[19] A certain hatred can also be seen in a letter to his mother dating back to his visit to Pavia in August 1492, when, speaking of Beatrice, he wrote: "she is not a greater than me, but she is much bigger!

[20] These frictions were perhaps also linked to the fact that Ludovico had initially asked for Isabella's hand, in 1480, and that this had not been possible because, only a few days earlier, Duke Ercole had officially promised it to Francesco Gonzaga.

[21] Despite everything, in 1492 she was very close to Beatrice in a difficult moment of her pregnancy, that is when she was suddenly struck by an attack of malarial fevers, and in 1495 she went again to Milan to assist her sister in her second birth and also baptized her nephew Francesco.

[25] Others instead defined Beatrice's attitude towards her sister as "complexed second child"[26] because in the letter of congratulations to Isabella for the birth of little Eleonora - who, being female, incredibly disappointed her mother - she added the greetings of her little son Hercules to "soa cusina", despite not having the child yet turned one year of age, something that historians such as Luciano Chiappini interpreted as a sort of mockery, of "refined malice", "a slap given with grace and grace".

He wrote to his wife to give it to his sister-in-law, but Isabella replied that she was not so willing to cede this honor to her sister and, with the excuse that she lacked a mule, begged her husband to invent some expedient.

Meanwhile, it occurred to her to procure "a femina de partito", that is, a high-ranking prostitute, to Francis, saying to do it "for a good cause and to avoid greater evil", that is to say to preserve her brother-in-law and sister from the terrible malfrancese, but perhaps also to ingratiate herself with him.

[30] Having also received different educations, the two sisters were the opposite of each other: Isabella, more like her mother, was sweet, graceful and a lover of tranquility; Beatrice, more like her father, was impetuous, adventurous and aggressive.

These judgments were not separated from a blatant contempt for the second daughter, as in the case of Alessandro Luzio, who writes: "The luck that made play of this Sforza, making him pass from the brightest heights to the darkest abysses of misery, had in April 1480 exchanged a beneficial star for a sinister meteor".

[34] In truth, other historians, including Rodolfo Renier himself, Luzio's colleague, judged that Beatrice was the most suitable wife for Ludovico, since she knew, with her own audacity, to instill courage in her insecure consort, and acquired political depth already in her early youth, so much so as to be decisive in situations of greatest danger, while Isabella could boast a role in this sense only in the years of maturity.

[40] Her long, fine hair was dyed a fashionable pale blonde and her eyes were described as "brown as fir cones in autumn, scattered laughter".

When in 1496 the second daughter Margherita was born, Isabella was so angry that she wrote to her husband, who was then fighting the French in Calabria, a letter in which she blamed him, declaring that she did nothing but reap the fruits of his sown.

[43] In his capacity of captain general of the Venetian armies, Francesco often was required to go to Venice for conferences that left Isabella in Mantua on her own at La Reggia, the ancient palace that was the family seat of the Gonzagas.

[47] At about the same time, Isabella had given birth to a daughter, Ippolita, and she continued to bear him children throughout Francesco and Lucrezia's long, passionate affair, which was more sexual than romantic.

She further displayed shrewd political acumen in her negotiations with Cesare Borgia, who had dispossessed Guidobaldo da Montefeltro, duke of Urbino, the husband of her sister-in-law and good friend Elisabetta Gonzaga in 1502.

To improve the well-being of her subjects she studied architecture, agriculture, and industry, and followed the principles that Niccolò Machiavelli had set forth for rulers in his book The Prince.

She was present during the catastrophic Sack of Rome, when she converted her house the Palazzo Colonna, into an asylum for approximately 2,000 people (including clerics, nobles and common citizens) fleeing the Imperial soldiers.

Her huge palace was the only place safe from attacks, because her son Ferrante Gonzaga was a general in the invading army and she herself had good relationship with the emperor.

[60] The alleged beauty of Isabella attracted the attention of the king of France, Charles VIII, who asked the chaplain Bernardino of Urbino about her features and attempted to arrange a meeting with her.

[73] Judgments less imbued with praise, indeed very harsh, were instead expressed by Pope Julius II in disagreement with Isabella's conduct, even went so far as to call her "that ribald whore".

[77][78] In painting she had numerous famous artists of the time work for her, including Giovanni Bellini, Giorgione, Leonardo da Vinci, Andrea Mantegna (court painter until 1506), Perugino, Raphael, Titian, Antonio da Correggio, Lorenzo Costa (court painter from 1509), Dosso Dossi, Francesco Francia, Giulio Romano, and many others.

[79] In parallel she contracted the most important sculptors and medallists of her time, i.e. Michelangelo, Pier Jacopo Alari Bonacolsi (L'Antico), Gian Cristoforo Romano, and Tullio Lombardo.

[87] In 1495 she refused with absolute rigor to pose for Mantegna in the Madonna della Vittoria – where her figure was provided next to that of her husband – since in the past the painter had portrayed her "so badly done" – in a painting that in fact has not survived – "which has none of my similarities".

However, the negative judgment of the Marquise was not due to Mantegna's inability to portray her similar to the truth, as she herself writes, but to the opposite lack: of not knowing how to "well counterfeit the natural", that is idealize.

Her husband Francesco had to pose alone and Mantegna remedied the disturbance of the symmetry by painting, in place of the Marquise, St. Elizabeth, his eponymous saint.

Evidence in favor of Isabella as the subject of the famous work includes Leonardo's drawing 'Isabella d'Este' from 1499 and her letters of 1501–1506 requesting the promised painted portrait.

[102] Further arguments focus upon the mountains in the background indicating the native origin of the subject,[103] and the armrest in the painting as a Renaissance symbol used to identify a portrait as that of a sovereign.