John, 6th Duke of Braganza

João I
D. João I; Palace of the Dukes of Braganza
Duke of Braganza
Tenure	22 September 1563 – 22 February 1583
Predecessor	Teodósio I
Successor	Teodósio II
Born	1543 Vila Viçosa, Alentejo, Kingdom of Portugal
Died	22 February 1583 Vila Viçosa, Vila Viçosa Municipality, Kingdom of Portugal
Spouse	Infanta Catherine of Guimarães
Issue among others...	Teodósio II
House	House of Braganza
Father	Teodósio I
Mother	Isabel of Lencastre
Religion	Roman Catholicism

Dom João I of Braganza (1543 – 22 February 1583) was the 6th Duke of Braganza and 1st Duke of Barcelos, among other titles. He is known pushing the claims of his wife, Infanta Catherine of Guimarães, to the throne of Portugal.

In 1563 he married his 1st cousin Infanta Catherine, daughter of Prince Edward, Duke of Guimarães and Isabel of Braganza (João's aunt).

After the disaster of the Battle of Ksar El Kebir, where heirless King Sebastian of Portugal died, the aged Cardinal Henry of Portugal had become King. Because Henry was old and was not allowed to have legitimate children, a dynastical crisis occurred even before the death of the Cardinal. The Duke of Braganza supported his wife's claim to the throne (she was a granddaughter of King Manuel I). Philip II of Spain (another grandson of Manuel I and also claimant to the throne), tried to bribe him to abandon his wife's pretensions, offering him the Vice-Kingdom of Brazil, the post of Grand-Master of the Order of Christ, a license to send a personal ship to India every year, and the marriage of his eldest son Teodósio of Braganza to one of his daughters (either Isabella Clara Eugenia or Catherine Michelle). The Duke of Braganza, influenced by his wife, refused the proposal.

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