Margaret of Savoy was the last HabsburgVicereine of Portugal from 1634 to 1640. In Portuguese she is known as Duquesa de Mântua, being by marriage the Duchess of Mantua and Montferrat. She was also regent of Montferrat during the minority of her daughter from 1612.
As the couple had no surviving male issue, Duke Francis' next brother succeeded him in the Duchy of Mantua, whereas in the Duchy of Montferrat he was succeeded by his three-year-old daughter Maria, because it had been historically inherited by females, as it was a margraviate. Indeed, it had been brought to the Mantuan princely dynasty by the marriage of Margherita Paleologa, Margravine of Montferrat, in 1531. Accordingly, Maria's claims were asserted and Dowager Duchess Margaret required to be made her regent in Montferrat. This was a contested inheritance - Maria was a minor for the next decade - and ultimately, Duke Francis' brothers failed to produce any legitimate issue, and the entire inheritance became subject to Mantuan War of Succession. Duchess Margaret's daughter Maria was in 1627 married to Charles, the eldest son of the distant Gonzaga heir-male, in order to join two of the Mantuan claims. They had to wage war, but in the end their line prevailed and they commanded universal recognition as Dukes of Mantua and Montferrat.
Vicereine of Portugal
Upon the death in 1633 of her maternal aunt, Archduchess Isabella Clara Eugenia, ruler of the Low Countries, her brother Victor Amadeus became heir to the rights of their maternal grandmotherElisabeth of Valois, eldest daughter and heiress of Henry II of France and Catherine of Medici. She had ancestral links to Portugal: two of her great-grandmothers had been daughters of king Manuel I of Portugal. . In 1635, after the demise of the Count of Basto, she was named by her cousin Philip IV of Spain Vicereine of Portugal, at the time in a dynastic union with Spain, where she moved to in 1636. This nomination was the result of the efforts of Diogo Soares, member of the Council of Portugal at Madrid, a friend of the Count-Duke of Olivares and a relative of Miguel de Vasconcelos who, in 1635, would be named secretary of state of Portugal. As a result of the Portuguese revolution of 1640, Vasconcelos was assassinated and the Duchess of Mantua tried to calm the Portuguese people during demonstrations in the Portuguese Terreiro do Paço. The Portuguese proclaimed the Duke of Braganza as their new king. Margaret was surrounded in her headquarters in Lisbon, and her support collapsing, the new potentate allowed her to depart to Spain. She died in Miranda de Ebro in 1655, her daughter Duchess Maria of Rethel and Montferrat surviving her, with two grandchildren, of whom the daughter Eleanor had in 1651 become the Holy Roman Empress and the son Charles in 1637 the reigning duke of Mantua. At her death, both her grandchildren had already produced great-grandchildren for her.