Battle of Jena-Auerstedt (1806): Prussia's Sudden Collapse

The Battle of Jena-Auerstedt was a pair of battles fought on 14 October 1806 in Thuringia, central Germany, in which Napoleon’s French armies destroyed the army of the Kingdom of Prussia. While Napoleon defeated one Prussian force at Jena, Marshal Louis-Nicolas Davout defeated the main Prussian army at Auerstedt, about 20 kilometres to the north. Within weeks Prussia, once the military model of Europe, had collapsed.

Background: Prussia goes to war

Prussia had stayed neutral during the war of 1805 that ended with the Battle of Austerlitz. Afterwards Napoleon forced it into an alliance and gave it Hanover, the German territory of the British king. In 1806, however, Napoleon created the Confederation of the Rhine under French control and was reported to be offering Hanover back to Britain in peace talks.

Angered and alarmed, a war party around Queen Louise pushed King Frederick William III to fight. Prussia joined Russia, Britain, Saxony and Sweden in the Fourth Coalition and on 26 September 1806 sent Napoleon an ultimatum demanding that French troops withdraw west of the Rhine. Prussia mobilised before Russian help could arrive, and its army, still trained in the methods of Frederick the Great, had changed little since his death in 1786.

The campaign

Napoleon moved first. In early October the Grande Armee, about 180,000 strong, advanced through the Thuringian Forest in three parallel columns, a formation he called a bataillon carre. On 10 October Marshal Jean Lannes defeated a Prussian advance guard at Saalfeld, where Prince Louis Ferdinand of Prussia was killed.

The French were now moving round the Prussian left flank towards Berlin. The Prussian commanders decided to retreat north-east. The main army under the elderly Duke of Brunswick, accompanied by the king, marched towards Auerstedt, while Prince Friedrich Ludwig of Hohenlohe covered the withdrawal near Jena with a second army.

The battles of 14 October

Jena

On 13 October Lannes’s corps reached the Landgrafenberg plateau above the town of Jena. During the night French troops hauled guns up the steep slopes, and by morning Napoleon had a strong force on the heights. He believed he was facing the main Prussian army.

The battle began in fog on the morning of 14 October. Napoleon fed in more and more troops, eventually bringing up some 90,000 men, not all of whom were engaged, against about 38,000 under Hohenlohe. Prussian infantry stood in close lines in the open and was shot down by French skirmishers and artillery. In the early afternoon a relief force of about 15,000 under General Ernst von Ruchel arrived too late and was routed in turn. The Prussian and Saxon army broke and fled towards Weimar, with Marshal Joachim Murat’s cavalry in pursuit.

Auerstedt

Meanwhile Davout, with the III Corps of about 26,000–27,000 men, had been ordered to march around the Prussian flank. Near Hassenhausen, close to Auerstedt, he ran into the main Prussian army of roughly 60,000–63,000 men under Brunswick.

Davout’s three divisions under Generals Gudin, Friant and Morand came into action one after another and formed squares against repeated cavalry attacks led by Field Marshal Gebhard von Blucher. Early in the battle Brunswick was shot through the eyes and mortally wounded, and the Prussian command fell into confusion. By early afternoon Davout counter-attacked and the Prussians withdrew, only to run into the fugitives from Jena. Davout lost about a quarter of his corps.

Marshal Jean-Baptiste Bernadotte’s I Corps, between the two battlefields, took part in neither battle, a failure for which Napoleon criticised him heavily.

Why Prussia lost

Prussia’s army still enjoyed the reputation won by Frederick the Great, but it had not fought a major war for a decade and its methods had barely changed. Its senior commanders were old: the Duke of Brunswick was 71, and Field Marshal Wichard von Mollendorf, who accompanied the army, was over 80. Command was divided between the king, Brunswick, Hohenlohe and a council of advisers, and decisions were slow and often changed.

Prussian infantry fought in rigid lines trained for volley fire, with few light troops able to skirmish in open order. Supplies depended on fixed magazines and slow baggage trains. The French, by contrast, were organised in self-contained corps, each able to fight alone for a day until others arrived, and they moved fast by living off the country. Their skirmishers and artillery repeatedly broke up Prussian lines before the main attacks.

Prussia’s diplomacy was also badly timed. It went to war before its Russian ally was ready to help, and the Saxon army that fought beside it was small and soon changed sides.

By the numbers

Figures are estimates and vary between historians.

The pursuit and the fall of Berlin

The French pursuit was one of the most relentless in military history. Erfurt surrendered on 16 October. Napoleon entered Berlin on 27 October 1806, after giving Davout’s corps the honour of marching in first. Hohenlohe surrendered with his remaining troops at Prenzlau on 28 October, Blucher capitulated near Lubeck on 7 November, and the great fortress of Magdeburg gave up on 11 November.

Frederick William III and Queen Louise fled to East Prussia. At Berlin, on 21 November, Napoleon issued the decree that began the Continental System against British trade. The war continued into 1807 against Russia and the remnants of Prussia until the Treaties of Tilsit, under which Prussia lost about half of its territory and population.

Key people

• Napoleon, who directed the campaign and won at Jena.
• Louis-Nicolas Davout, whose victory at Auerstedt made his name; Napoleon later created him Duke of Auerstedt.
• Charles William Ferdinand, Duke of Brunswick, the Prussian commander, who died of his wounds on 10 November 1806.
• Prince Hohenlohe, the defeated commander at Jena.
• Gebhard von Blucher, a cavalry general who would later become one of Napoleon’s most determined opponents.

Legacy: the Prussian reforms

The scale of the defeat shocked Prussia’s leaders into change. Reformers led by Baron vom Stein and Karl August von Hardenberg abolished hereditary serfdom by the October Edict of 1807, introduced town self-government and modernised the state. Military reformers including Gerhard von Scharnhorst, August von Gneisenau and the young Carl von Clausewitz reorganised the army, opened the officer corps to talent and prepared for a national army.

These changes helped Prussia play a major part in Napoleon’s defeat at the Battle of Leipzig in 1813 and at Waterloo in 1815. The philosopher G. W. F. Hegel, who was finishing his Phenomenology of Spirit in Jena, saw Napoleon ride through the town on 13 October and famously described him in a letter as the world-soul on horseback.

Timeline

• 1806, 26 September: Prussian ultimatum to Napoleon.
• 1806, 10 October: Battle of Saalfeld; Prince Louis Ferdinand is killed.
• 1806, 14 October: Battles of Jena and Auerstedt.
• 1806, 27 October: Napoleon enters Berlin.
• 1806, 28 October: Hohenlohe surrenders at Prenzlau.
• 1806, 7 November: Blucher surrenders near Lubeck.
• 1806, 21 November: Berlin Decree launches the Continental System.
• 1807, 9 July: Franco-Prussian Treaty of Tilsit.

Why it matters

Jena-Auerstedt showed how far Napoleon’s flexible corps system had outpaced the rigid armies of the old monarchies. It reduced Prussia to a dependent state for six years, but it also set off the reforms that turned Prussia into a modern power and, in the long run, the leader of German unification.