Waterloo is one of the most famous battles in history and it has given rise to a vast and varied literature. The strategy and tactics of the battle and the entire Waterloo campaign have been analysed at length. The commanders, manoeuvres and critical episodes, and the intense experiences of the men who took part, have all been recorded in minute detail. But the organization, structure and fighting strength of the armies that fought in the battle have received less attention, and this is the subject of Philip Haythornthwaite\'s detailed, authoritative and engaging study. Through a close description of the structure and personnel of each of the armies he builds up a fascinating picture of their makeup, their methods and their capabilities. The insight he offers into the contrasting styles and national characteristics of the forces that came together on the Waterloo battlefield gives a fresh perspective on the extraordinary clash of arms that ended the Napoleonic era.