King John VI was the ruler of Portugal from 1816 until his death in 1826. He became king after the death of his mother, Queen Maria I, and faced significant challenges during his reign, including the Napoleonic Wars. To escape the French invasion, he and the royal family fled to Brazil in 1807, where he established a court in Rio de Janeiro. After returning to Portugal in 1821, John VI struggled with political unrest and the push for constitutional reforms. His reign saw the transition from an absolute monarchy to a constitutional monarchy, which ultimately led to his death and the ascension of his son, Pedro IV.