History of Portugal (1834–1910)
Militant Republicans and their allies in the Carbonária were not willing to remain in the shadows of the constitutional monarchy. Between 4–5 October 1910, members of the Carbonária, republican youth, and elements of the army instigated a coup d'état against the already weak constitutional monarchy. The young king and his family, after a few miscues, escaped from the Palace in Mafra to exile in England. On the morning of 5 October 1910, the Republic was declared from the balcony of Lisbon City Hall, ending eight centuries of monarchy in Portugal.
House of Aviz
Joaquim Veríssimo Serrão, writing in 1956 and counting António as a king, dates the end of the dynasty's rule of Portugal as occurring in 1581–1582. The Cortes of Tomar had acclaimed Philip II of Spain as Philip I of Portugal in 1581, subsequently António's forces were utterly defeated at sea by Álvaro de Bazán at the Battle of Ponta Delgada off São Miguel Island in the Azores, on 26 July 1582. António then retreated to Terceira, where he supervised the raising of levies for defense, but in November he left Angra do Heroísmo en route to France to persuade the French to furnish more troops, 800 of which arrived in June 1583. Philip had despatched Santa Cruz with an overwhelming force which left Lisbon on 23 June, and reaching sight of São Miguel some time after 7 July, finally reduced the Azores to subjection.