John ascended to the throne when Brazil was still a colony of Portugal (they were called the United Kingdom to show that all the parts were equal).
He was forced into Exile to Brazil, where his son was born. This son later became the regent of Brazil and declared independence.
While it was mostly his son that lead to the independence of the country, John IV allowed it, by leaving his son as a regent and by focusing on Portugal.
Finally, in 1925, while he was still the monarch, Portugal accepted Independence of Brazil.
