The Snare by Rafael Sabatini

Across the frontier in the northwest was gathering the third army of invasion, some sixty thousand strong, commanded by Marshal Massena, Prince of Esslingen, the most skilful and fortunate of all Napoleon's generals, a leader who, because he had never known defeat, had come to be surnamed by his Emperor "the dear child of Victory."

Wellington, at the head of a British force of little more than one third of the French host, watched and waited, maturing his stupendous strategic plan, which those in whose interests it had been conceived had done so much to thwart. That plan was inspired by and based upon the Emperor's maxim that war should support itself; that an army on the march must not be hampered and immobilised by its commissariat, but that it must draw its supplies from the country it is invading; that it must, in short, live upon that country.