The Trocadéro is an area of Paris, France, in the 16th arrondissement, across the Seine from the Eiffel Tower. The hill of the Trocadéro is the hill of Chaillot, a former village.
The place was named in honour of the Battle of Trocadero, in which the fortified Isla del Trocadero, in southern Spain, was captured by French forces led by the Duc d’Angoulême, son of the future King of France, Charles X, on August 31, 1823. France had intervened on behalf of King Ferdinand VII of Spain, whose rule was contested by a liberal rebellion. After the battle, the autocratic Spanish Bourbon Ferdinand VII was restored to the throne of Spain.
François-René de Chateaubriand said “To stride across the lands of Spain at one go, to succeed there, where Bonaparte had failed, to triumph on that same soil where the arms of the fantastic man suffered reverses, to do in six months what he couldn’t do in seven years, that was truly prodigious!”
Nowadays the square is officially named Place du Trocadéro et (and) du 11 Novembre (for the WWI armistice), although it is usually simply called the Place du Trocadéro.
Source : wikipedia