As you must know, day 1 of December is holiday in Portugal. In this day the Day of the Restoration of Independence is commemorated.
You want to know reason?
Everything started in ends of séc. XVI: the king of Portugal was D. Sebastião.
In 1578, D. Sebastião died in the battle of Alcácer-Quibir, in the north of Africa. Portugal was, thus, without king, therefore D. Sebastião was very new and not yet it had children, did not have direct heirs for the Portuguese crown.
Thus, who went up to the throne was Cardinal D. Enrique, who was uncle-grandfather of D. Sebastião. But it only reigned during two years because nor all were in accordance with it as new king.
But attention: these things never are simple, had many candidates and this gave much confusion…
In 1580, in the Cuts To take, Filipe II, king of Spain, were chosen as the new king of Portugal. The reason for the choice was simple: Filipe II was son of the princess D. Isabel and also grandson of Portuguese king D. Manuel, therefore it had right to the throne.
In this height, it was frequent to happen marriages between people of the cuts of Portugal and Spain, what it made with that had Portuguese Spaniard that they belonged to the family real Portuguese and who belonged to the Spanish real family.
During 60 years, a period was lived in Portugal that was known in History as “Domain Phillipino”. After the reign of Filipe II (I of Portugal), it came the governação of Filipe III (II of Portugal) and Filipe IV (III of Portugal). These kings governed Portugal and Spain at the same time, as one only country.
The Portuguese had finished for rebelling themselves against this situation and, in day 1 of December of 1640, they had ended the reign of the Spanish king in a palaciano blow (a blow alone to knock down the king and its government).
In the height, the Duchess of Mântua was vice-queen and Miguel de Vasconcelos was notary of the Farm of the Kingdom. He had immense to be able.
In day 1 of December of 1640, the Restoratives had killed it shot and were defenestrado (shot of the window below) in the Paço of the Ribeira.
Filipe III abandoned the throne of Portugal and the Portuguese had chosen D. João IV, duke of Bragança, as new king.
Day 1 of December every year passed to be commemorated as the Day of the Restoration of the Independence of Portugal, since the throne came back toward a Portuguese king.