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.
Portugal–Spain relations
In 1974 the dictatorship of the "Estado Novo" was brought to an end by a military "coup" known as the Carnation Revolution. This left Spain increasingly isolated from the rest of Europe, which lasted until the death of Franco a year later, after which Spain returned to being a constitutional monarchy and embraced parliamentarism. The PREC that had followed the Carnation Revolution in Portugal came to an end in 1976 and Portugal also became a democracy.