just a two-month-old baby, French envoys proposed to marry Isabella with a future son of Francis I of France in exchange for Sigismund's support in the upcoming elections for the Holy Roman Emperor. Sigismund supported Charles V, but Bona continued to pursue a French marriage for Isabella. She hoped that King of France would install his son and Isabella in the Duchy of Milan which Bona claimed as her inheritance. In 1524, Hieronymus Łaski negotiated an anti-Turkish alliance with the French; among the provisions was marriage of Isabella and Henry, second son of Francis I. But this alliance failed after Francis was taken prisoner in the Battle of Pavia. Bona then pursued an Italian marriage. Isabella of Naples, Isabella's grandmother, sent envoys to Poland to propose marriage to Francesco II Sforza, newly installed Duke of Milan. However, Sigismund refused as the duchy was contested and Francesco's hold was tenuous. Bona then proposed Federico II Gonzaga, Duke of Mantua, but he chose Margaret Paleologa as she brought March of Montferrat as her inheritance. Sigismund wanted a Habsburg marriage. In 1530, he proposed Maximilian, eldest son of Archduke Ferdinand of Austria, but they refused as Isabella was eight years older than the groom. When Habsburgs wanted to stop the proposed marriage between Isabella and John Zápolya, they proposed Ludovico, eldest son of Charles III, Duke of Savoy, but he died in 1536. Around 1531, a plan emerged to wed Isabella to John Zápolya, Voivode of Transylvania and King of Hungary. When Louis II of Hungary was killed in the Battle of Mohács in 1526, Hungary was divided between pro-Habsburg Royal Hungary and pro-Zápolya Eastern Hungarian Kingdom. The parties were engaged in the Little War in Hungary. Zápolya had sustained his claim only by gaining support from and becoming vassal of the Ottoman Empire. Bona Sforza, ardent opponent of the Habsburgs, supported Zápolya and tried to convince her husband Sigismund to provide military support and Isabella's hand. Sigismund, whose first wife was Zápolya's sister Barbara, refused, not wanting to upset the Habsburgs and doubting Zápolya's ability to hold onto his throne. Eventually, Sigismund relented on a condition that a peace treaty was concluded between Zápolya and the Habsburgs. The Treaty of Nagyvárad was signed in February 1538 in part due to Sigismund's requirement. Archduke Ferdinand of Austria and Zápolya agreed to divide Hungary between themselves and that Ferdinand was to inherit Zápolya's territory