With several members of this group and in cooperation with Costa's Republican Party, João (then styled Viscount of Ameal) was involved in the failed Municipal Library Elevator Coup, one month before the Lisbon Regicide. The coup derives its name from the large public elevator designed by  (Raoul Mesnier du Ponsard) and owned by Ameal near Lisbon City Hall which served as the conspirators' headquarters, and where many would be arrested on the afternoon of 28 January 1908. Its organisers were opposed to the administrative dictatorship of Prime Minister João Franco, and to King Carlos I's perceived protection of Franco's Liberal Regeneration Party.