José died of smallpox at the age of 27, causing his younger and ill-prepared brother,[1] Infante João, to become heir-apparent, Prince Regent to their mentally ill mother and eventually King.

João's regency and reign would be a turbulent one, seeing the Napoleonic invasion of Portugal and the loss of the Portuguese Empire's largest and wealthiest colony, Brazil.

José was born at the Real Barraca where the Palace of Ajuda in Lisbon stands today.

At the time of his birth, his parents were the Prince and Princess of Brazil, his mother the Heir presumptive of the king.

Upon José's death, his younger brother Infante John became heir-apparent to the throne and thus the new Prince of Brazil.