After warily watching nearly three years of factional struggles in Spain over the government, the international powers at the Congress of Verona (October 1822), alarmed by the capture of Spain's Kind Ferdinand VII (1784-1833) by armed revolutionaries opposed to absolutism, authorized France to intervene in the conflict and restore Ferdinand to his throne, despite Britain's objection. On April 17, 1823, French forces led by Louis Antoine de Bourbon, duke of Angouleme (1775-1844), crossed the Pyrenees into Spain, welcomed by the Basques and Catalonians. The duke dispatched a force to besiege San Sebastian while he launched an attack on Madrid, Spain's capital, held by the revolutionaries. The rebel government withdrew to Seville, Mardrid's military commander secretly capitulated and fled to France, and the leaderless Madrid garrison could not keep out the French, who seized the city and installed a Spanish-chosen regent pending Ferdinand's return. From there, the French moved south to besiege the revolutionaries under Colonel Rafael del Riego y Nunez (1785-1823) at Cadiz, where the Cortes (national legislature) had taken Ferdinand. Riego's forces suffered defeat at the Battle of Trocadero on August 31, 1823, and when Cadiz fell to the French on September 23, 1823, Ferdinand was handed over to them and restored to the throne. Renouncing his prior promise of amnesty for the revolutionaries, the king order ruthless measures of reprisal against them while French troops stood by helplessly.