"Napoleón en Chamartín" by Benito Pérez Galdós is a novel published in 1874. It is the fifth installment in the first series of the Episodios Nacionales. The story follows Gabriel de Araceli, who has evolved from a cabin boy to a heroic figure, as he witnesses Napoleon's siege of Madrid. The French emperor, enraged by his humiliation at Bailén, establishes his headquarters in Chamartín de la Rosa. Meanwhile, the people of Madrid prepare to defend their city against the disciplined Napoleonic forces, despite overwhelming odds. (This is an automatically generated summary.)