The Portuguese Empire was the first Global Empire in world history and was and by some could still be considered one of the longest running and most dynamic colonial empire in history. The Empire Began with using new developments in naval and navigational technology to secure a long string of trading posts. These trading posts strung along from Lisbon to Nagasaki.
Almost by a string of Luck the nation of Portugal discovered Brazil and began to establish more than trading posts and established true colonies in Brazil intermarrying, establishing cities, reaping beneficial resources back to the mother country. The empire continued to prosper for quite a long time establishing a monopoly on resources from the Americas and monopoly on trade from Asia which eventually led to the massive influx of Riches to these mother countries establishing their dominance in colonial politics until the French, Dutch, and British managed to wrestle control of Indian and Asian trade routes ending the Monopoly and beginning Portugal's steady decline over a period of over 100 years.
Following the Separately administered empires of the Iberian Union and the loss of the asian trade routes, the Portuguese Empire maintained itself for decades until the wave of revolutions began sweeping the Americas. In this instance Portugal lost Brazil in a short and relatively small revolution in which the empire maintained only a few of its remaining overseas colonies. Portugal following the loss of Brazil entered into a constant state of stagnation and decline which only ended near the tail end of the 19th century.
War of Succession
In the late 1870's Brazil and its emperor, officially claimed the throne to Portugal aimed at taking the nation with the closest cultural ties to itself and strengthening the empire. This came about just after the reorganizing of Succession rules to the Empire putting Dom Pedro II's potential grandson on the throne and with this Dom Pedro's want to put the empire in a much better situation before he took the throne ended with a claim to succession to the throne of Portugal.
The Brazilian claim surprisingly gathered much support bringing the British Empire, and the United States behind the effort. The War for succession began when Portugal officially recognized another heir to the throne and essentially tried to scrap Brazil's claim. This ended in a war in which a surprising invasion of Portugal by Brazilian forces seized the city of Porta and an expert maneuver by the British through Spain after they attempted to prevent them, ended in the capture of Lisbon and the Royal family. This ended in the full surrender of Portugal and her colonies to Brazil and Dom Pedro II of House Braganza the king of Portugal, and lastly Portugal being organized as a Dominion of the empire.
Dominion of Portugal
The Dominion itself and its current ruling government following the War is led de facto by the Emperor of Brazil, and a Dominionary council which oversees much of the local happenings of Portugal and keeps order among other things to the Homeland of Brazil.
The Dominion itself has become a relatively stable, and essential part of Brazils Colonial ambitions as it is a major stopping point for trade ships in a Triangle trade with Brazil, Africa, and Portugal. The Dominion itself maintains its own armed forces supplied by Brazil, and jointly trains with the Imperial army.
The Dominion itself is very prosperous and has a much better and more dynamic economy than it was when portugal was an independant nation. The Economy thanks to Brazils timely involvement and now industrialization to a degree the Nation is much better off than it was just a few years ago.