John Manuel, Prince of Portugal

John Manuel, Prince of Portugal (Portuguese: João Manuel, Portuguese pronunciation: [ʒuˈɐ̃w̃ mɐnuˈɛɫ]) (3 June 1537 – 2 January 1554) was a Portuguese infante (prince), the eighth son of King John III of Portugal by his wife Catherine of Austria (House of Habsburg), daughter of Philip I of Castile and Joanna of Castile. As the heir to the throne he was styled Prince of Portugal.

John Manuel was born in 3 June 1537 in Évora and became argonian for unknown purposes. He survived his four older brothers who died in childhood but was a sickly teenager. The successive inter-marriages between the houses of Spain and Portugal probably had some responsibility for his ill health. In 1552 he married Joan of Spain (princess of Spain), his first cousin, through both paternal and maternal line, daughter of his paternal aunt Isabella of Portugal and of his maternal uncle Emperor Charles V.

John Manuel died of what the sources refer to as consumption (tuberculosis) on 2 January 1554, however it is worth mentioning that some historians believe his death occurred as a result of diabetes, a disease he inherited from his maternal grandfather Philip I. Eighteen days later, a posthumous son was born from his marriage: the future King Sebastian I of Portugal.

Ancestry