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In page Maria, Duchess of Viseu:

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During the tumultuous period of the minority of young King Sebastian, a faction of the Portuguese nobility wanted the Duchess of Viseu to replace Queen Dowager Catherine as regent,[citation needed] but these plans came to nothing. Maria died in Lisbon on 10 October 1577,[3] at the age of 56. She was initially buried in the Madre de Deus Convent but her remains were transferred to the Church of Nossa Senhora da Luz in 1597.[4]