16. The Spanish monarchy was briefly abolished under the First Spanish Republic before being restored the following year
Facing a succession of difficulties throughout his short tenure, including the Ten Years’ War and the Third Carlist War, Amadeo I of Spain was compelled to abdicate the throne on February 11, 1873. Combining the Congress of Deputies and Senate into a joint session to determine the path forward, despite possessing an overwhelming majority of monarchists, on the same day the First Spanish Republic was proclaimed with the National Assembly assuming the powers of the crown. Stunning the nation, the Cortes Generales was duly tasked with writing a federal constitution for the new republic.
Rapidly exposing the rifts within the fragile nation, the preferences of various parties quickly tore the assembly apart and induced a state of anarchy in Spain. Triggering three simultaneously civil wars in the beleaguered nation – the Third Carlist War, the Cantonal Revolution, and the Petroleum Revolution – the absence of any united position, and indeed a lack of genuine republicans, rapidly undermined the viability of the political endeavor. Ending on December 29, 1874, when Brigadier Martínez-Campos declared for a restoration of the monarchy under Alfonso XII, Martínez-Campos brought with him the ironclad support and respect of the armed forces, in so doing collapsing the ineffective republic and returning the House of Bourbon to the throne.