Lisbon Regicide
The assassination of King Carlos and the Prince Royal was the effective end of a constitutional monarchy in Portugal (later confirmed by the 5 October 1910 revolution). The regime functioned for another 33 months with growing agitation and demands for reform (although considerably less than in the future First Republic). It cannot be denied that the weak and permissive attitude in the Government of Acclamation was an incentive for the Republican Party to attempt another coup. The assassinations did not change the system of government; instead, they delayed the change.
Portuguese succession crisis of 1580
On July 24, 1580, António proclaimed himself King of Portugal in Santarém, followed by acclamation in several locations throughout the country; his domestic government lasted for 20 days, until he was defeated in the Battle of Alcântara by Habsburg armies led by the Duke of Alba. After the fall of Lisbon, he purported to rule the country from Terceira Island, in the Azores, where he established a government in exile until 1583; António even had coins minted—a typical assertion of sovereignty and royalty. Some authors consider him the last monarch of the House of Aviz (instead of Cardinal-King Henry) and the 18th King of Portugal. His government in Terceira island was only recognized in the Azores, whereas on the continent and in the Madeira Islands power was exercised by Philip II, who was acclaimed king in 1580 as Philip I of Portugal and recognized as official king by the Cortes of Tomar in 1581. The new king's election was carried on condition that the kingdom and its overseas territories should remain separate from Spain and keep their own laws and Cortes.