His death led to the Portuguese succession crisis of 1580 and ultimately to the 60-year Iberian Union that saw Portugal share a monarch with Habsburg Spain.

Early in his life, Henry took Holy Orders to promote Portuguese interests within the Catholic Church, then dominated by Spain.

[7][8] The Cardinal-King died in the Royal Palace of Almeirim, on his 68th birthday, without having appointed a successor, leaving only a regency to care for the kingdom.

[9] One of the closest dynastic claimants was King Philip II of Spain who, in June 1580, sent the Duke of Alba to claim Portugal by force.

[10] Lisbon soon fell, and Philip was elected king of Portugal at the Portuguese Cortes of Tomar in 1581— on the condition that the kingdom and its overseas territories would retain their autonomy.