In February 1869, he convoked the Cortes Constituyentes; he was appointed successively as president of the executive, Prime Minister of Spain, and Regent from 3 October 1868 to 18 June 1869.
Serrano ruled impartially, respecting the independence of the Cortes and cabinets.
He acceded to their selection of Amadeus I of Savoy as king, although he would have preferred Montpensier.

As soon as Amadeus reached Madrid, after the death of Prim, Serrano consented to form a coalition cabinet, which lasted only a few months.
Serrano resigned and took the command of the Italian king's army against the Carlists in northern Spain.

He tried to form one more cabinet under King Amadeus as the 65th Prime Minister of Spain on 6 June 1872, but resigned on 12 June when that monarch declined to give his ministers dictatorial powers and sent for Ruiz Zorrilla.
His mistakes led to Amadeus abdicating the throne on 11 February 1873.
In February 1869, he convoked the Cortes Constituyentes; he was appointed successively as president of the executive, Prime Minister of Spain, and Regent from 3 October 1868 to 18 June 1869. Serrano ruled impartially, respecting the independence of the Cortes and cabinets. He acceded to their selection of Amadeus I of Savoy as king, although he would have preferred Montpensier.
As soon as Amadeus reached Madrid, after the death of Prim, Serrano consented to form a coalition cabinet, which lasted only a few months. Serrano resigned and took the command of the Italian king's army against the Carlists in northern Spain.
He tried to form one more cabinet under King Amadeus as the 65th Prime Minister of Spain on 6 June 1872, but resigned on 12 June when that monarch declined to give his ministers dictatorial powers and sent for Ruiz Zorrilla. His mistakes led to Amadeus abdicating the throne on 11 February 1873.
Francisco Serrano, 1st Duke of la Torre