[2] The third child and second son of King John V, Joseph became his father's heir as an infant when his older brother, Pedro, Prince of Brazil, died.

The Lisbon earthquake allowed the Marquis of Pombal to consolidate power and also caused King Joseph to develop claustrophobia, refusing to live in a walled building ever again.

Joseph succeeded to the Portuguese throne in 1750, when he was 36 years old,[6] and almost immediately placed effective power in the hands of Sebastião José de Carvalho e Melo (in 1770, the king made him Marquis of Pombal).

France and Spain sent an ultimatum in order to force Portugal to abandon its alliance with Great Britain and close her ports to British ships.

King Joseph refused to submit and asked for British help since both Portugal and its army were in a very poor condition, mainly because of the great 1755 Lisbon earthquake.

As synthesized by historian Walter Dorn: … Effort of the Bourbon powers to set up the beginnings of a 'continental system' by sending a summons to Portugal to close her ports to British ships and exclude Englishmen from Brazil trade.

But the Portuguese minister, the Marquis of Pombal, refused, and with the assistance of Count Lippe and the English General Burgoyne broke the offensive of the Spanish invading army.

The capital was eventually rebuilt at great cost, and an equestrian statue of King Joseph still dominates the Praça do Comércio, Lisbon's main plaza.

With Joseph's death on 24 February 1777, the throne passed to his daughter, Queen Dona Maria I, and his brother and son-in-law, King Dom Peter III.