H ow to stop this monster? The main players on the continent were the Russians, the Austrians, and the Prussians, while the Royal Navy controlled the oceans. Aware of the failures of the two previous attempts at anti-French coalitions, the young and idealistic Czar Alexander of Russia took the lead in the effort to form a new coalition, the so-called third coalition, which is the main topic of this volume. Alexander wanted a stable system in Europe, based on international law; he had first hoped that Napoleon could be hemmed in by defensive alliances but reached the conclusion that Napoleon could not be contained and therefore had to be fought and defeated.

Alexander first approached the British. Though the Brits were Napoleon’s most implacable foes, a number of obstacles had to be overcome — the British were skeptical of the czar’s idealism and suspicious of Russian intentions toward Turkey, while the Russians objected to the British naval policy of confiscating the cargo of neutral shipping — before a treaty could be signed. The Brits could be relied upon to provide financing — Napoleon would forever rail against “Pitt’s gold” — but at that time, they did not have an army on the continent. For that, continental allies were needed. Alexander had first hoped to persuade Prussia’s King Frederick William iii into joining the game when Napoleon invaded Hanover. But Prussia was poor and threadbare, its military leadership ancient and stuck in Frederick the Great’s parade manual. In fact, so far had military expenses been cut that the Prussians relied on showing visiting dignitaries their parade troops, hoping to impress them with military theater. Besides, Frederick William feared the Austrians and the Russians almost as much as he feared the French; he was determined to stay neutral.

Alexander then turned to Francis, the emperor of Austria. Francis’s Austro-Hungarian empire had also seen better days, and he feared that a mobilization on his part would invite a French attack. What abruptly changed his mind and brought the third coalition into being was Napoleon’s decision in 1804 to make Italy a kingdom and put himself on its throne, leaving the day-to-day running of the place to his stepson, Eugène Beauharnais. To Napoleon, this was just a bit of routine housekeeping, but to Francis it presented a mortal threat to Austria, as it put the French armies permanently within striking distance of Vienna. With a heavy heart, he started to mobilize.

At this point Napoleon was up on the Channel coast at Boulogne with his Army of England, consisting of 200,000 men, busily preparing for the invasion of Britain, for which an armada of small boats and barges had been assembled to get the troops across. He always regarded Britain as his main enemy, and its destruction was priority one. According to Kagan, the coalition’s mobilization moves took him by surprise and annoyed him intensely; he did not want war in that part of Europe just then.

Hence, Napoleon waited to the very end to see whether his useless admiral, Pierre-Charles de Villeneuve, would show up in the Channel with his fleet to support his landing in Britain. But de Villeneuve, whom Napoleon derided as a Jean-foutre (French for klutz), judged his fleet too vulnerable and failed to arrive.

The book thus dismisses those historians who claim that the Army of England was just an elaborate ruse, that Napoleon never intended to invade Britain, that in fact he had planned the whole time to strike in the middle of Germany. This, according to Kagan, is the view of those for whom Napoleon is incapable of miscalculation — a group, incidentally, to which Napoleon belonged himself. In 1810 he asserted to Count Metternich that “I would never have been stupid enough to undertake an assault on England. The army assembled at Boulogne was always an army aimed at Austria.” But, Kagan cautions, Napoleon on Napoleon should always be taken with a grain of salt: His invasion set-up was far too elaborate to be a decoy operation.

While inept at sea, Napoleon certainly knew how to move on land. His plan was to go to the center of Europe and clobber the Austrians before the Russians arrived. His great advantage was that he had a fully trained and equipped army at his disposal whose skills had been honed to a fine edge over two years. Leaving a shadow force on the Channel, he renamed his Army of England “Le Grande Armée” and sent it racing to Germany, covering 20 to 30 miles a day, fully equipped with drummers placed at the head, middle, and rear of every brigade column, drumming them along.

Showing up in unexpected places was very much the Napoleonic way; as he put it, “Marches are war.” The army’s movements were masked by a screening force of light cavalry under the command of his brother-in-law, the flamboyant gascon Marshal Joachim Murat, who was known for his courage and his extravagant self-designed uniforms.

As befits a man who has taught at West Point, Kagan is particularly good on the rather unglamorous topic of logistics, without which no army will get anywhere. Napoleon was meticulous in planning his routes, calculating what each would take in ammunition and horses, and the separate courses his army corps were going to take; as they had to live off the land, the routes had to vary. Living off the land enables an army to march fast without relying on slow carts of food supplies and pre-positioning of depots. The drawback, of course, is that it upsets the local populations, especially when you claim to have come to liberate them from their oppressive rulers.

The Austrians and the Russians had the numbers in their favor, with some 350,000 men, of whom Austria would provide 235,000 and Russia 115,000. But mere numbers did not faze a man like Napoleon, whose favorite game was to split his opponents up, isolate them, and then defeat them in detail before their overall superiority could be brought to bear.

Napoleon’s Austrian opponent was Baron Karl von Mack, in charge of an army of 80,000. Mack was a self-made man of huge ambition and self-confidence who had risen from private all the way to quartermaster general of the Austrian army. He had promised his master that he could mobilize in two months, where others claimed it would take six.

As Kagan says, generals should be self-confident. But Mack’s was the kind of overconfidence that springs from insecurity. High-strung and in permanent crisis mode, demanding instant execution, Mack would issue a blizzard of orders, some of them contradictory, without checking to see whether they were implemented.

Above all, according to Kagan, Mack lacked what Clausewitz calls “coup d’oeil,” an eye for battle; that is, an ability to read a situation and intervene at exactly the right moment. Mack had a fondness for complicated maneuvers, exhausting his officers and troops in futile marches and counter marches, in contrast to Napoleon, who preferred keeping things simple, which is always advisable when the bullets start to fly.

To make matters worse, the Austrians — who had only met Napoleon as a tactical commander in Italy before and not at the strategic level — prepared for battle in Italy, where they had an army of 95,000 men and where they believed Napoleon would strike again. When he realized that Napoleon was coming right at him in Germany, Mack should have changed his plan, and fast.

But Mack was surrounded by aristocrats who would have been only too pleased to see him fall flat on his face; under the circumstances, he could not admit to having made a mistake and therefore did very little to modify his war plan. As a result, his army was encircled in the battle of Ulm, and on October 17, 1805, he surrendered without having put up a proper fight; he was subsequently sentenced to death by an Austrian court martial but was imprisoned instead and eventually pardoned.