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.
United Kingdom of Portugal, Brazil and the Algarves
Although Pedro's abdication of the Portuguese Crown to Maria II was provided for even in the Constitution issued on 29 April 1826, the original deed of abdication, signed on 2 May 1826 contained conditions; however, those conditions were subsequently waived, as the abdication was later declared final, irrevocable, accomplished and fully effective by a decree issued by Pedro on 3 March 1828, just a few months before Infante Miguel's usurpation of the Throne and the start of the Portuguese Civil War (in accordance with a decree issued on 3 September 1827, Infante Miguel replaced Infanta Isabel Maria as Regent of Portugal on 26 February 1828, and he initially agreed to govern in the name of the Queen, but on 7 July 1828 he had himself proclaimed King with retroactive effect, assuming the title of Miguel I; Maria II would only be restored to the Throne in 1834, at the conclusion of the Civil War). In any event, Pedro's unconditional confirmation of his abdication reinforced the impossibility of a new union between Portugal and Brazil.