In 1820 Major Rafael de Riego led a revolt among troops quartered in Cadiz while awaiting embarkation to America. Garrison mutinies were not unusual, but Riego issued a pronunciamiento or declaration of principles, to the troops, which was directed against the government and which called for the army to support adoption of the 1812 constitution. Support for Riego spread from garrison to garrison, toppling the regalist government and forcing Ferdinand to accept the liberal constitution. Thepronunciamiento, distributed by barracks politicians among underpaid members of an overstaffed officer corps, became a regular feature of Spanish politics. An officer or group of officers would seek a consensus among fellow officers in opposing or supporting a particular policy or in calling for a change in government. If any government were to survive, it needed the support of the army. If apronunciamiento received sufficient backing, the government was well advised to defer to it. This "referendum in blood" was considered within the army to be the purest form of election because the soldiers supporting a pronunciamiento--at least in theory--were expressing their willingness to shed blood to make their point. A pronunciamiento was judged to have succeeded only if the government gave in to it without a fight. If it did not represent a consensus within the army and there was resistance to it, the pronunciamiento was considered a failure, and the officers who had proposed it dutifully went into exile.
French intervention, ordered by Louis XVIII on an appeal from Ferdinand and with the assent of his conservative officers, brought the three years of liberal government under the 1812 constitution--called the Constitutional Triennium (1820-23)--to an abrupt close. The arrival of the French was welcomed in many sectors. Ferdinand, restored as absolute monarch, chose his ministers from the ranks of the oldafrancesados.
The inept rule of Spain King Ferdinand VII (1784-1833), who refused to accept the liberal constitution of 1812, provoked widespread unrest, particularly in the army. The king sought to reconquer the Spanish colonies in South America that had recently successfully revolted and consequently deprived Spain of a major source of revenue. At Cadiz, Spain, in January 1820, troops who had assembled for an expedition to America were angry over infrequent pay, bad food, and poor quarters and mutinied under the leadership of Colonel Rafael del Riego y Nunez (1785-1823). Pledging fealty to the 1812 constitution, they seized their commander, moved into nearby San Fernando, and then prepared to march on Madrid, the capital. Despite the rebels' relative weakness, Ferdinand accepted the constitution on March 9, 1820, ushering in a period of popular rule. But in this liberal atmosphere, political conspiracies of both right and left proliferated. Liberal revolutionaries stormed the king's palace and virtually made Ferdinand a prisoner for the next three years. A mutiny occurred in the Madrid garrison, and civil war erupted in the regions of Castile, Toledo, and Andalusia. The Holy Alliance (Russia, Austria and Prussia) refused Ferdinand's request for help, but the Quadruple Alliance (Britain, France, Holland and Austria) at the Congress of Verona (October 1822) gave France a mandate to intervene and restore the Spanish monarchy. French troops invaded Spain, captured Madrid, and drove the revolutionaries south to Cadiz and Seville. On August 31, 1823, rebel forces were routed in a battle near Cadiz, and soon after, the French freed Ferdinand, who had been taken from Madrid as a captive, and placed him on the throne. Unexpectedly, he took ruthless revenge on his opponents, revoked the 1812 constitution, restored absolutism (despotism) to Spain.