Although the coup was prevented by government forces, it failed to capture all the conspirators, which contributed to the assassination of the monarch Carlos I of Portugal and the heir to the throne, the Prince Royal, Luís Filipe.

Since King Carlos I of Portugal had decided to support the Liberal-Regenerator leader João Franco and allow him to run the government as an administrative dictatorship (without parliament, but maintaining civil liberties), the parties in the Cortes had vocally rebelled.

João Franco was also interested in marginalizing the Republicans by co-opting many of the planks of the other parties in order to form a program that would reduce the existing political instability.

The election of 5 April 1908, which could have ushered in a legislative victory for João Franco's Liberal-Regenerators, and possibly installed a functional parliament, united the leaders of the Dissidency and Republican Party in a conspiracy to take power by force.

Various versions of the plan existed, although they all shared the same goal of removing the dictator João Franco without forcing the intervention of the military, and thus escalating the conflict into a civil war.

A few, still belligerent conspirators, attempted to attack these forces in the bairro of Rato, in the civil parish of Alcântara, at the Campo de Santana and along the Rua da Escola Politécnica: one policeman was killed.

Although the assassins ignored João Franco's carriage, he was held responsible for the lack of police security and a naive over-confidence that allowed the monarch to travel in an uncovered landau.

The traditional parties were able to impose an acclamation solution, with the establishment of a unity government presided over by an independent (Francisco Joaquim Ferreira do Amaral), the ostracising of João Franco's supporters, and the repeal of Francist decrees.

The acclamation policies were effectively a surrender: many of the conspirators were released from prison, the assassins (who had been killed in the square) were eulogized as martyrs, and the criminal investigation was rendered ineffective.