On the 6th of March 1821 Santarosa and three associates had an interview with the prince, and on the 10th they carried out the military "pronunciamiento" which proclaimed the Spanish constitution.
He took office under Marshal Serrano during 1874, after the pronunciamiento of General Pavia had done away with the Cortes and the Federal Republic. He vainly attempted to crush the Carlists in 1874, and to check the Alphonsist military conspiracy that overthrew the government of Marshal Serrano at the end of December 1874.
At the close of the war the queen regent and her ministers attempted to elbow out Espartero and his followers, but a pronunciamiento ensued in Madrid and other large towns which culminated in the marshal's accepting the post of prime minister.
O'Donnell's pronunciamiento in 1856 put an end to the Cortes, and the militia was disarmed, after a sharp struggle in the streets of the capital.
On New Year's Day 1820 he made his pronunciamiento with his regiment at the village of Cabezas de San Juan.