The Empire of Brazil was a 19th-century state that broadly comprised the territories which form modern Brazil and Uruguay. Its government was a representative parliamentary constitutional monarchy under the rule of Emperors Dom Pedro I and his son Dom Pedro II. A colony of the Kingdom of Portugal, Brazil became the seat of the Portuguese colonial Empire in 1808, when the Portuguese Prince regent, later King Dom João VI, fled from Napoleon's invasion of Portugal and established himself and his government in the Brazilian city of Rio de Janeiro. João VI later returned to Portugal, leaving his eldest son and heir, Pedro, to rule the Kingdom of Brazil as regent. On 7 September 1822, Pedro declared the independence of Brazil and, after waging a successful war against his father's kingdom, was acclaimed on 12 October as Pedro I, the first Emperor of Brazil. The new country was huge but sparsely populated and ethnically diverse.