Marriage and children
Eleonora's marriage was arranged by her godmother and namesake, the dowager Holy Roman Empress, who maintained close ties with her niece, the Duchess-Regent Maria, and became the main supporter of her election as wife of Ferdinand III, Holy Roman Emperor; previously, the dowager empress was also able to arrange the marriage of Duke Charles II of Mantua (Eleonora's brother) with Archduchess Isabella Clara of Austria (a member of the Tyrolese branch of the House of Habsburg) in 1649.
During the nuptial negotiations, the emperor promoted the following conditions: the Duchy of Mantua would continue its loyalty to the interests of the Holy Roman Empire, the bride would retain her possible inheritance rights over the Duchy of Montferrat, and a dowry of 400,000 thalers. Duke Charles II agreed with only minor changes: Mantua would maintain its loyalty to the Holy Roman Empire only if the alliance did not bring negative consequences to the duchy, and the bride's dowry would be paid in several installments in the next years.
The marriage by proxy was solemnized on 2 March 1650 at the Basilica Palatina di Santa Barbara, where the emperor was represented by his ambassador, Count Johann Maximilian von Lamberg. The celebrations lasted until 22 March, when Eleonora, accompanied by some relatives, traveled from Mantua to Vienna. The cortege arrived at the Austrian city of Villach, where the bride said goodbye to her relatives and in the company of her godmother the dowager empress continued the trip to Wiener Neustadt, where on 30 April 1651 there took place the official wedding ceremony between Eleonora and Holy Roman Emperor Ferdinand III. After the ceremony, the emperor gave his new wife the family jewels and a gift of 50,000 florins. For Ferdinand III, this was his third marriage; he had had children from both previous unions.
In spite of the great difference in age, the marriage was a happy one. The active and sweet nature of the young empress helped her gain the sympathy of all members of the Imperial family. She established an excellent relationship with all her stepchildren. She learned German, and the emperor Italian. Together they participated in religious and secular ceremonies. Genuine piety of both spouses did not prevent them from patronizing literature and music activities, like visits to theaters or hunting, which was one of the passions of the empress. In her portrait by Frans Luycx, Eleonora is depicted in the image of Diana, the ancient goddess of hunting.
During her marriage, Eleonora gave birth to four children, two of whom survived into adulthood:
Theresia Maria Josepha (27 March 1652 – 26 July 1653), Archduchess of Austria.
Eleonora Maria Josepha (21 May 1653 – 17 December 1697), Archduchess of Austria; she married first Michael Korybut Wiśniowiecki, King of Poland, and then Charles V, Duke of Lorraine.
Maria Anna Josepha (30 December 1654 – 4 April 1689), Archduchess of Austria; she married John William, Elector Palatine.
Ferdinand Joseph Alois (11 February 1657 – 16 June 1658), Archduke of Austria.