Diogo of Portugal (1425–1443) was a
Portuguese royal prince, who briefly served as
Constable of Portugal and Master of the
Order of Santiago.
Diogo was the eldest son of
John, Lord of Reguengos de Monsaraz,
Infante of Portugal, and of his wife (and niece)
Isabella of Barcelos. Through his father, Diogo was the grandson of King
John I of Portugal
John I ( pt, João uˈɐ̃w̃ 11 April 1357 – 14 August 1433), also called John of Aviz, was King of Portugal from 1385 until his death in 1433. He is recognized chiefly for his role in Portugal's victory in a succession war with Casti ...
and through his mother, the grandson of
Afonso of Barcelos (future first
duke of Braganza).
John of Reguengos had been the master of the
Order of Santiago since 1418 and
Constable of Portugal since 1431. Upon John's premature death in October 1442, the Portuguese
regent,
Peter of Coimbra
Infante D. Pedro, Duke of Coimbra KG (; en, Peter), (9 December 1392 – 20 May 1449) was a Portuguese ''infante'' (prince) of the House of Aviz, son of King John I of Portugal and his wife Philippa of Lancaster, daughter of John of Gaunt. I ...
decided to appoint John's son Diogo as the new Constable of Portugal. Diogo was elected on 24 January 1443, as 11th Master of the Order of Santiago. Diogo died a few days later, without issue. Peter appointed his own son, also named
Peter, to succeed him as constable.
These appointments were contested by Diogo's half-uncle (and grandfather),
Afonso, Count of Barcelos. Afonso had married the daughter of the late beatified constable
Nuno Álvares Pereira, and believed their son,
Afonso of Ourem, had superior rights to succeed as Constable of Portugal. Peter of Coimbra challenged Barcelos and Ourem to provide documentary proof of the legitimacy of this lineage (which they were unable to produce). Peter of Coimbra attempted to mollify them by creating the title of
Duke of Braganza, and investing it in Afonso of Barcelos. However, this failed to heal the breach between Peter and Afonso, which would only grow with time.
Ancestry
References
External links
Genealogical information on Diogo, Constable of Portugal (in Portuguese)
Bibliography
"Nobreza de Portugal e do Brasil" – Vol. I, page 297. Published by Zairol Lda., Lisbon 1989.
Portuguese infantes
House of Aviz
1425 births
1443 deaths
15th-century Portuguese people
Constables of Portugal
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