In 1805 the recently crowned Emperor Napoleon ended the Peace of Amiens and began the War of the Third Coalition against Great Britain and Sweden. He had amassed his army at Boulogne for an invasion but the French Navy couldn’t guarantee a safe crossing of the English Channel and the weather was turning steadily worse (sounds familiar). In September, Austria and Russia entered the Coalition, and this would lead to a serious and overwhelming threat from the east if the Austrian and Russian armies ever linked up. So Napoleon struck first. He secured an alliance with Bavaria and then moved to invade Austria before Russian troops could arrive. Austria mobilized and invaded Bavaria, but Napoleon’s La Grande Armee moved much quicker, due to its use of the highly effective Corps System.

Napoleon’s corps were just larger versions of the combined arms divisions he pioneered in his earlier Italian campaigns. He found his flexible combined arms infantry divisions, consisting of infantry battalions supported by two cavalry squadrons and four or five artillery batteries under the direct command of the division commander, routinely outfought Austrian and Italian pure infantry formations that lacked supporting arms. Napoleon’s corps were the next logical step.

Napoleon’s corps were standardized, self-sufficient, combined arms formations about the same size as an army in Frederick the Great’s time, fifty years before. Revolutionary zeal and increased conscription brought about by Imperial France’s “nation in arms” allowed Napoleon to field several corps at the same time. In October 1805, Napoleon had eight corps committed against Austria in the War of the Third Coalition: seven infantry and one cavalry. The cavalry corps was tasked specifically for reconnaissance, security, pursuit, and exploitation. Each infantry corps was comprised of about 25,000 men consisting of the aforementioned infantry divisions, and cavalry and artillery pure brigades, with supporting specialists such as engineers, pontoon bridges, and supply trains, all under a trusted subordinate capable of independent command.

These corps’ commanders were Napoleon’s chosen ones: the Marshals of France, and they were promoted strictly on merit and military efficacy. Generals could be political appointees or promoted because of birth, such as Napoleon’s brother Jerome, but never a marshal. The 26 men chosen over the years by Napoleon to be Marshals of France came from all walks of life, and were a collection of talent and ability rarely seen in history. Only the Diadochi, Jesus’ Apostles, the Genghis Khan’s generals, the viziers of Suleiman, the Sun King’s advisors, and America’s Founding Fathers occupy the same historical pedestal. Napoleon trusted his marshals implicitly to carry out his mission orders and did not micromanage them with directives. With the self-sufficiency and inherent initiative of the corps system, and without the burden of a supply tail due to the French Army’s liberal use of foraging, the Marshals and their corps maneuvered much more quickly and with greater agility than France’s enemies.

Austria, like the rest of Europe, still maintained the army-level unit, an unwieldy formation of about 100,000 men, as the lowest level of synchronization and integration between combined arms. Furthermore, the Austrian commander, General Mack, had no equivalent to Napoleon’s Marshals. Unlike Napoleon whom issued orders just to his corps (eight in the Ulm campaign), Mack’s headquarters had to issue orders to each and every regiment, which was more than a hundred, with each order handwritten and delivered beforehand. Finally, the Austrians were still tied to fixed supply lines, according to the rules of European limited warfare of the eighteenth century which sought to shield civilians from the effects of war. Needless to say, the Austrians simply couldn’t respond to the speed and agility of Napoleon’s corps.

Napoleon’s La Grande Armee marched 500 miles in 40 days. In the first weeks October 1805, Mack managed to only make it to Ulm, on the Danube in the Black Forest just northwest of Munich before he was surrounded by Napoleon’s marshals. He was out maneuvered to the north and to the south, and anytime he attempted to riposte, his detachments were thoroughly beaten by the brilliantly led use of synchronized combined arms inherent in the individual French corps. On 14 October 1805, French Marshal Michel Ney routed the Austrians at the Battle of Elchingen, which completed the trap. After a few small battles against the disorganized Austrians, Mack surrendered his remaining troops on 20 October. Only Prince Schwarzenberg, Napoleon’s future brother in law, managed to break out of the encirclement and join the Russians. The Austrians lost more than 60,000 men, Napoleon, but 2,000.

Napoleon said of Ulm, “I have destroyed the Austrian army by simply marching.”

The road to Vienna was open. The heart of Central Europe, the Austrian Empire, the German Confederation, and the Holy Roman Empire, created by Charlemagne a thousand years before, lay within Napoleon’s grasp.