King Amadeo I of Spain abdicates, triggering the proclamation of the First Spanish Republic.

Amadeo I, also known as Amadeus, was an Italian prince who reigned as King of Spain from 1870 to 1873. The only king of Spain to come from the House of Savoy, he was the second son of Victor Emmanuel II of Italy and was known for most of his life as the Duke of Aosta, the usual title for a second son in the Savoyard dynasty.