General Leopoldo O'Donnell takes control of the Spanish government on July 14–15, bringing an end to the bienio progresista.

Baldomero Espartero had resigned power in O'Donnell's favor, and Isabella II has asked him to form a government as the 44th Prime Minister of Spain.

For his new administration, O'Donnell forms the Unión Liberal Party, which is designed to combine Progressive, Moderate, and Carlist factions.

O'Donnell will attempt to define moderate policies for Spain with this new party, advocating laissez-faire policies and confiscating church land.

He will soon dismissed on October 12 after only a few months in powe.