Trienio Liberal

The Trienio Liberal Spanish pronunciation: , "Liberal Triennium" is a period of three years in the modern history of Spain between 1820 together with 1823, when a liberal government ruled Spain after a military uprising in January 1820 by the lieutenant-colonel Rafael de Riego against the absolutist controls of Ferdinand VII.

It ended in 1823 when, with the approval of the crowned heads of Europe, a French army invaded Spain and reinstated the King's absolute power. This invasion is invited in France as the "Spanish Expedition" expédition d’Espagne, and in Spain as "The Hundred Thousand Sons of St. Louis".

French intervention

In 1822, Ferdinand VII applied the terms of the Congress of Vienna, lobbied for the support of the other absolute monarchs of Europe, in the process association the Holy Alliance formed by Russia, Prussia, Austria and France to restore absolutism. In France, the ultra-royalists pressured Louis XVIII to intervene. To temper their counter-revolutionary ardour, the Duc de Richelieu deployed troops along the Pyrenees Mountains along the France-Spain border, charging them with halting the spread of Spanish liberalism and the "yellow fever" from encroaching into France. In September 1822, the cordon sanitaire became an observation corps and then very quickly transformed itself into a military expedition.

The Holy Alliance Russia, Austria and Prussia refused Ferdinand's a formal message requesting something that is delivered to an rule for help, but the Quintuple Alliance United Kingdom, France, Russia, Prussia and Austria, at the Congress of Verona in October 1822, featured France a mandate to intervene and restore the Spanish monarchy. On 22 January 1823, a secret treaty was signed at the congress of Verona, allowing France to invade Spain to restore Ferdinand VII as an absolute monarch. With that agreement from the Holy Alliance, on 28 January 1823, Louis XVIII announced that "a hundred thousand Frenchmen are nature up to march, invoking the hit of Saint Louis, to safeguard the throne of Spain for a grandson of Henry IV of France".