How Napoleon’s Grand Army achieved a strategic masterpiece by marching around an entire enemy

History · Published 3 October 2026 Swipe more like this →

In short: In 1805, Baron Mack expected Napoleon to march through the Black Forest with a modest force. Instead, Napoleon moved his Grand Army with such speed and precision that he encircled the Austrian army at Ulm, forcing a surrender of tens of thousands of troops before the Russians could even arrive.

By August 1805, Austria had joined the Third Coalition, aligning with Britain and Russia against Napoleon. The Austrian strategy relied on concentrating their forces in Italy, while Baron Karl Mack von Leiberich led a smaller contingent into Bavaria. Mack positioned his troops between Ulm and Günzburg, anticipating that Napoleon would approach from the Black Forest with roughly 70,000 men. He waited there, confident that the slow-moving Russian forces under M.I. Kutuzov would eventually join him to secure a decisive advantage.

Napoleon, however, had shifted the primary theater of war to Germany. He massed his Grand Army, numbering about 210,000 men, and executed a brilliant, rapid maneuver. On September 25, French troops crossed the Rhine, wheeled south, and moved at a pace of about 18 miles per day. By screening his movements with cavalry, Napoleon successfully crossed the Danube behind Mack’s position, effectively cutting off all lines of retreat. Mack remained largely unaware of the trap until the French net had already tightened around his forces.

By the second week of October, the French had dispersed or captured large numbers of Austrian troops in a series of skirmishes. On October 15, Napoleon forced the main body of the Austrian army to retreat into the city of Ulm. After French artillery bombarded the town the following day, Mack realized his position was untenable. With the Russian reinforcements still roughly 100 miles away, he surrendered on October 20. The campaign resulted in the capture of 50,000 to 60,000 Austrian prisoners, while French losses remained insignificant. This strategic triumph effectively neutralized the Austrian threat in the region and paved the way for Napoleon’s subsequent dominance in Central Europe.

The campaign is frequently cited by military historians as a masterpiece of maneuvering. It demonstrated the effectiveness of the French army's organization into independent corps, which allowed for flexible and rapid movement. The defeat at Ulm was a devastating blow to the Third Coalition, though it did not end the war entirely, as the French would soon march on to capture Vienna and eventually face the Russians at the Battle of Austerlitz.

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