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The Battle of Austerlitz

Corps d'Armee and Ulm

In order to prevent being overwhelmed by an allied army, Napoleon decided to seize the initiative and attack first by driving his army from Boulogne near the English Channel to the Rhine river. The army had a front of 260km, showing a structural change from the armies of old.


Generals generally tried to keep their forces concentrated. A concentrated force is advantageous as it is more likely to overwhelm the enemy army and more resistant to a potential ambush. A wide front would be contrary to this idea were it not for the development of the corps d' armee


General Karl Mack

The corps was essentially a mini army consisting of infantry, artillery and cavalry divisions of 15-30,000 men. Each corps was able to operate for a limited time independently until reinforcements from other corps could arrive.


One corps would be able to hold an enemy army in place giving Napoleon time to concentrate his forces and launch an offensive. He did not have to continuously have his army concentrated which allowed for the wide front seen in his advance to the Rhine. This allowed the army to both cover more ground and increase movement speed.


The best example of the effectiveness of this system was Napoleon’s beginning manoeuvres in the Austerlitz campaign.

In Napoleon’s previous European campaigns, the focus of France’s war efforts had been in Northern Italy. The allies expected Napoleon to yet again campaign in this theatre.


He did not. Instead, he marched his 200,000 strong Grande Armee eastwards into Central Germany. The front stretched froms Hannover to Wurttemberg and the right wing concentrating along the middle Rhine. 

The Austrian general Mack had advanced his army prematurely and had found himself isolated from the rest of the allied force. His plan had been to defend Ulm and contain the French until he was reinforced by the Russian army. He had not expected a French offensive in Central Germany.


Map of Ulm Manoeuvre

The  French were able to move rapidly, and Napoleon completely surrounded Mack’s army at Ulm and forced 60,000 soldiers to surrender. This was a devastating blow to the Allies only six weeks into the war.


The corps system deserves much of the credit. Due to its self-sustaining nature, a corps was durable enough to spread out into a wide front and could defend itself when gathering food. 

The Ulm victory did not bring about an end to the war. While Napoleon had inflicted a significant setback for the Austrians, he had not yet dealt with the Russian army. Worse still, the Austrians and the Russians had linked up bolstering Allied numbers. The French were in a precarious situation. They were far from France, and as a result the lines of communications connecting the army to its supply base were stretched. With winter approaching, Napoleon needed to force a decisive battle quickly to stand a chance of winning.

Up Next: The Battle of Austerlitz


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