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No general in history has a greater reputation for decisiveness than Napoléon Bonaparte. As a military leader he was the consummate man of action. He outthought contemporaries, not just in breadth of knowledge but by the lightning quickness of his mind. Napoléon was capable of instantly retrieving minor details or pieces of information to decisive effect on the battlefield. His greatest victories demonstrated these aspects of his genius. Even his disastrous final defeat at Waterloo in June 1815 was a close-run contest that might well have ended in French victory.

Among Napoléon’s most critical decisions, few had wider repercussions than his onslaught on Prussia and decisive victory at Jena-Auerstedt in October 1806. Prussian King Friedrich Wilhelm III had spent the first nine years of his reign on the sidelines of the European wars, refusing to commit to either side while eagerly watching for crumbs to enhance his domains. Napoléon astutely judged Friedrich Wilhelm a weakling whom he could bully at will. After the French emperor’s decisive victory over the Austrians and Russians at the Battle of Austerlitz in December 1805, he decided the time had come for a final settlement with the Prussians. With Austria out of the picture, Russia reeling eastward and Britain all but severed from the Continent, Prussia seemed the sole remaining threat to Napoléon’s domination of Europe.

There followed a diplomatic whirlwind in which Napoléon isolated the Prussians from their allies and then bullied and humiliated Friedrich Wilhelm into climbing off the fence and preparing for war. Not for a moment did the French emperor doubt the outcome. By reputation the Prussian army was the greatest in Europe—in quality if not in size. Frederick the Great’s exploits during the 1756–63 Seven Years’ War had astounded Europe. By 1806, however, the Prussian army was like a toy soldier, gaudy but brittle, and led by an ossified coterie of generals who had not conjured an original thought for 40 years. Administration was slipshod, and training based on antiquated principles. Perhaps worse, neither soldiers nor civilians felt any personal stake in the conflict with France.

Without waiting for Russian support, the overconfident Prussians occupied Saxony in September 1806 and established a 55-mile-long cordon reaching from the small university town of Jena in the east to Eisenbach in the west, intended to threaten French forces in Germany while protecting Berlin. Napoléon responded to these lumbering Prussian movements with his customary celerity, moving his forces rapidly around his enemy’s flank in a series of complicated but flawlessly executed maneuvers that ultimately propelled the French all the way to Jena. Quick as the slash of a sword, Napoléon had interposed his army between the Prussians and the approaching Russians, at the same time threatening Berlin. And as hoped, he had thrown the Prussians into a panic. They would have to fight Napoléon on ground of his choosing in order to protect their capital.

On October 14 Napoléon and his trusted Marshal Louis-Nicolas Davout attacked and shattered the Prussians at the twin battles of Jena and Auerstedt, destroying Friedrich Wilhelm’s forces in a veritable instant. Berlin fell shortly afterward. These battles, and the campaign that preceded them, marked one of the most decisive chapters in Napoléon’s legacy—not just for their short-term impact but for their long-term repercussions.

The defeat of Prussia inflated Napoléon’s sense of invincibility, leaving him deaf to the French people’s growing de- sire for peace and to the dissatisfaction of occupied Europe under French rule. Over the next few years he arrogantly overreached his forces in campaigns to Iberia and Russia that would weaken and eventually destroy his rule.

A hitherto obscure Prussian aide-de-camp who served in the Battle of Jena and afterward spent two years in French prisons, Carl von Clausewitz drew important conclusions from the battle. Napoléon, he decided, had conquered because of his ability to marshal the entire resources of the state. Henceforth, Clausewitz declared, military forces must serve as an extension of the state and of the nation. Once people were brought to believe that the fate of the army determined the fate of the state, every ounce of the nation’s energy would be bent toward victory. He had written a prescription for total war that would be realized on an unimaginably larger scale a century later during World War I.

Another man present during the Battle of Jena, German philosopher Georg Wilhelm Friedrich Hegel, said of Napoléon: “I saw the emperor—this world-soul—riding out of the city on a reconnaissance. It is indeed a wonderful sensation to see such an individual, who, concentrated here at a single point, astride a horse, reaches out over the world and masters it.”


Originally published in the March 2012 issue of Military History. To subscribe, click here.