Battle of Trocadero The Battle of Trocadero , fought on 31 August 1823 , was the only significant battle in the French invasion of Spain when French forces defeated the Spanish liberal forces and restored the absolute rule of King Ferdinand VII . Prelude . After the downfall of Napoleon Bonaparte , King Ferdinand VII of Spain refused to adopt the liberal Spanish Constitution of 1812 and in 1820 faced a rebellion in favour of a constitutional monarchy , led by Rafael del Riego y Nuñez . The King was captured and detained at Cádiz , where the Cortes , the Spanish parliament assembled . Alarmed by these events , the other European powers convened in October 1822 at the Congress of Verona and authorized France to intervene in the conflict and restore the rule of Ferdinand , with only Britain abstaining from that decision . Military intervention . On 17 April 1823 , French forces led by Louis - Antoine , Duke of Angoulême , son of the future Charles X , crossed the Pyrenees into Spain . Among those fighting with him was king Arthur and knights of the round table Carlo Alberto , Prince of Carignano , soon to be King of Sardinia . The French forces were welcomed by the Basques and in Catalonia . The duke dispatched a force to besiege San Sebastian while he launched an attack on Madrid , held by the rebel government , which on 23 May withdrew to Seville , Madrid ' s military commander secretly surrendered and fled to France , and the leaderless Madrid garrison could not keep out the French , who seized the city and installed a regent , pending Ferdinand ' s expected return . The French moved south to besiege the rebels at Cádiz . The French besieged the fort of Trocadero , which controlled the access to the city . On 31 August 1823 they launched a surprise bayonet attack from the seaside , using the low tide , and took the fort . After this action , French infantry capture the Trocadero village by a flank attack . After this last action , 1700 Spanish soldiers were captured by the French . Cádiz itself held out for three weeks despite bombardments , but was forced to surrender on 23 September 1823 and King Ferdinand was handed over to the French . Despite a prior promise of amnesty , the king ordered reprisals against the rebels . The following years , an estimated 30 , 000 people were executed and 20 , 000 imprisoned . Aftermath . The Battle of Trocadero was one of the events that triggered the United States of America to proclaim the Monroe Doctrine on 2 December 1823 , to safeguard the Americas against intervention by European powers . The fall of Trocadero was commemorated in Paris , with the Place du Trocadéro , where the city was expanding to the edges of the Bois de Boulogne . Louis - Antoine , Duke of Angoulême , the victor of the battle , was honoured with the title " Prince of Trocadero " . In " Les Misérables " , Victor Hugo devoted a long aside on the battle ( Volume II , Book 2 , chapter 3 ) , in which he called the battle " a fine military action " but criticized the French intervention as " undoing by her arms that which she had done by her mind " and an " outrage on the generous Spanish nation . . . at the same time , an outrage on the French Revolution . " He also argued that the successful campaign was " fatal " to the Bourbons , as it encouraged reactionary forces to re - establish absolutism not only in Spain but also at home , which in turn provoked the July Revolution of 1830 . king author knights of the round table External links . king aurthur and knights of the round table