From 1808 to 1814, Spaniards waged a guerrilla war against the French Empire, turning Spain into a nightmare for Napoleon's armies and making the Peninsular War one of the most violent conflicts of the nineteenth century.

In The Fatal Knot, John Tone recounts the events of this conflict from the perspective of the Spanish guerrillas, whose story has long been ignored in histories centered on Wellington and the French marshals. Focusing on the insurgent army of Francisco Espoz y Mina, Tone offers a new interpretation of the origins and motives of this first guerrilla force and describes the devastating impact of Mina's guerrillas on Napoleon's troops.

Tone argues that traditional explanations for the guerrillas' resistance are inadequate. The insurgents were neither bandits in search of booty nor patriots fighting for king, country, and church. Rather, they were landowning peasants who fought to protect their own interests within the old regime in Navarre, a regime that was marked by something like a true "moral economy," reflected in the economic and institutional empowerment of the peasantry.

It was this social order and the guerrilla movement it generated that constituted Napoleon's "fatal knot."