1805 campaign during the War of the Third Coalition
 War of the Third Coalition: ;br ;Ulm Campaign
 ;templatestyles src="Legend/styles.css" / ;  Napoleon in command ;templatestyles src="Legend/styles.css" / ;  Napoleon not in command
The Ulm campaign was a series of French and Bavarian military maneuvers and battles to outflank and capture an Austrian army in 1805 during the War of the Third Coalition. It took place in the vicinity of and inside the Swabian city of Ulm. The French , led by Emperor Napoleon, had 210,000 troops organized into seven corps and hoped to knock out the Austrian army in the Danube before Russian reinforcements could arrive. Rapid marching let Napoleon conduct a large wheeling maneuver, which captured an Austrian army of 60,000 under Feldmarschall-Leutnant (FML) Karl Freiherr Mack von Leiberich on 20 October at Ulm. The campaign is by some military historians regarded as a strategic masterpiece and was influential in the development of the Schlieffen Plan in the late 19th century. Napoleon himself wrote:
"four months of marching about, months of fatigue and wretchedness, have proved to me that nothing is more hideous, more miserable, than war. And yet our sufferings in the Guard are not to be compared with those of the line."
The victory at Ulm did not end the war since a large Russian army under Mikhail Kutuzov was near Vienna to defend the city against the French. The Russians withdrew to the northeast to await reinforcements and to link up with Austrian army units. The French moved aggressively forward and captured Vienna on 12 November. On 2 December, the massive Battle of Austerlitz, causing 24,000 to 36,000 casualties, removed Austria from the war. The resulting Treaty of Pressburg in late December brought the Third Coalition to an end and established Napoleonic France as the major power in Central Europe, which led to the War of the Fourth Coalition against the Kingdom of Prussia and Russia the following year.
Background.
Europe had been by then embroiled in the French Revolutionary Wars since 1792. After five years of war, the French Republic subdued the First Coalition in 1797. A Second Coalition was formed in 1798 but this too was defeated by 1801. Britain remained the only opponent for the new French Consulate. In March 1802, France and Britain agreed to end hostilities under the Treaty of Amiens. For the first time in ten years, all of Europe was at peace. There were many problems between the two sides and implementing the agreements that had been reached at Amiens seemed to be a growing challenge. Britain resented having to turn over all colonial conquests since 1793, and France was angry that British troops had not evacuated the island of Malta, as the treaty had promised. The tense situation only worsened since Napoleon sent an expeditionary force to crush the Haitian Revolution. In May 1803, Britain declared war on France.
Third Coalition.
In December 1804, an Anglo-Swedish agreement led to the creation of the Third Coalition. British Prime Minister William Pitt the Younger spent 1804 and 1805 in a flurry of diplomatic activity to form a new coalition against France. Mutual suspicion between the British and the Russians eased in the face of several French political mistakes, and by April 1805, the first two had signed a treaty of alliance. Having been defeated twice in recent memory by France and keen on revenge, Austria also joined the coalition a few months later.
French military preparations.
Prior to the formation of the Third Coalition, Napoleon had assembled the "Army of England", an invasion force that was meant to strike at the British Isles, around six camps at Boulogne in Northern France. Although they never set foot on British soil, Napoleon's troops received careful and invaluable training for any possible military operation. Although boredom quickly set in among the troops, Napoleon paid many visits to conduct lavish parades to maintain their morale.
The men at Boulogne formed the core for what Napoleon would later call ("The Great Army"). At the start, the French army had about 200,000 men organized into seven corps, which were large field units, containing about 36 to 40 cannon each and capable of independent action until other corps could arrive. On top, Napoleon created a cavalry reserve of 22,000 troopers organized into two cuirassier divisions, four mounted dragoon divisions and two divisions of dismounted dragoons and light cavalry, all supported by 24 artillery pieces. By 1805, the had grown to a force of 350,000, was equipped and trained. It possessed a competent officer class where almost all from sergeants to marshals had experience in the recent Revolutionary Wars.
Austrian military preparations.
Archduke Charles, brother of the Austrian Emperor, had started to reform the Austrian army in 1801 by taking away power from the "Hofkriegsrat" (Aulic Council), the military-political council responsible for decision making in the Austrian armed forces. Charles was Austria's most able field commander, but he was unpopular with the royal court and lost much influence when, against his advice, Austria decided to go to war with France.
Mack became the new main commander in Austria's army, instituting reforms on the infantry on the eve of war that called for a regiment to be composed of four battalions of four companies, rather than the older three battalions of six companies. The sudden change came with no corresponding officer training; new units were led by commanders who had not been given sufficient tactical training in using their units.
Austrian cavalry forces were regarded as the best in Europe, but the detachment of many cavalry units to various infantry formations precluded the hitting power of their massed French counterparts, who could be ordered by Napoleon to amass a whole corps of cavalry to influence the battle.
Campaign.
The Ulm campaign lasted for nearly a month and saw the French army under Napoleon deliver blow after blow to the confused Austrians. It culminated on 20 October with the loss of an entire Austrian army.
Austrian plans and preparations.
On 9 September 1805, an Austrian army directed by Mack but under the nominal command of General der Kavallerie Archduke Ferdinand Karl Joseph of Austria-Este crossed the frontier into the Electorate of Bavaria without a declaration of war. It was hoped that the Austrian army, would compel the Bavarian army to join the Third Coalition against France. However, the Bavarian elector had signed a secret treaty with France and moved his army north to Würzburg in order to rendezvous with French forces. By 18 September, Mack's army was arrayed near Ulm where it watched the Black Forest to the west. Mack expected that it would take the French two months to react, but Emperor Napoleon's Grand Army was already on the march and by 24 September it was on the Rhine River. 
Mack's initial deployment of the Austrian army was as follows. FML Johann Kollowrat with 24 battalions was posted at Ulm. FML Michael von Kienmayer guarded Mack's right rear on the Danube River at Ingolstadt with 6 battalions and 16 squadrons. The other forces lay farther south. They were FML Karl Philipp, Prince of Schwarzenberg with 21 battalions and 46 squadrons near Ravensburg, FML Franz Xaver von Auffenberg with 14 battalions and 8 squadrons at Kempten, FML Franz Jellacic with 19 battalions and 8 squadrons at Lindau on Lake Constance, and FML Franz von Werneck with 15 battalions and 8 squadrons at Landsberg am Lech. Altogether, the Austrian army in Bavaria numbered 66,000 infantry and 9,000 cavalry. Mack expected that the French army would attack from the west. 
Mack thought that Austrian security relied on sealing off the gaps through the mountainous Black Forest area in southern Germany that had witnessed much fighting during the campaigns of the French Revolutionary Wars. Mack believed that there would be no action in central Germany. Mack decided to make the city of Ulm the centerpiece of his defensive strategy, which called for a containment of the French until the Russians under Kutuzov could arrive and alter the odds against Napoleon. Ulm was protected by the heavily fortified Michelsberg heights, giving Mack the impression that the city was virtually impregnable from outside attack.
Fatally, the Aulic Council decided to make Northern Italy the main theater of operations for the Habsburgs. Archduke Charles was assigned 95,000 troops and directed to cross the Adige River with Mantua, Peschiera, and Milan as the initial objectives. The Austrians based an army of 72,000 men on Ulm. Nominally commanded by Archduke Ferdinand, the army's real authority was Mack. Austrian strategy required that Archduke John with 23,000 troops secure the Tyrol and provide the link between his brother Charles's army and his cousin Ferdinand's army. The Austrians also detached individual corps to serve with the Swedish in Pomerania and the British in Naples, though these were designed to confuse the French and divert their resources.
French plans and preparations.
In both the campaigns of 1796 and 1800, Napoleon had envisaged the Danube theater as the central focus of French efforts, but in both instances the Italian theater became the most important. The Aulic Council thought Napoleon would strike in Italy again. Napoleon had other intentions: 210,000 French troops would be launched eastwards from the camps of Boulogne and would envelop General Mack's exposed Austrian army if it kept marching towards the Black Forest. Meanwhile, Marshal Murat would conduct cavalry screens across the Black Forest to fool the Austrians into thinking that the French were advancing on a direct west-east axis. The main attack in Germany would be supported by French assaults in other theaters: Marshal Masséna would confront Charles in Italy with 50,000 men of the "Armée d'Italie", St. Cyr would march to Naples with 20,000 men, and Marshal Brune would patrol Boulogne with 30,000 troops against a possible British invasion.
Murat and Henri Gratien, Comte Bertrand conducted reconnaissance between the area bordering the Tyrol and the Main as Anne Jean Marie René Savary, chief of the planning staff, drew up detailed road surveys of the areas between the Rhine and the Danube. The left wing of the would move from Hanover in northern Germany and Utrecht in the Netherland to fall on Württemberg; the right and center, troops from the Channel coast, would concentrate along the Middle Rhine around cities like Mannheim and Strasbourg. While Murat was making demonstrations across the Black Forest, other French forces would then invade the German heartland and swing towards the southeast by capturing Augsburg, a move that was supposed to isolate Mack and interrupt the Austrian lines of communication.
The French invasion.
On 22 September Mack decided to hold the Iller line anchored on Ulm. In the last three days of September, the French began the furious marches that would place them at the Austrian rear. Mack believed that the French would not violate Prussian territory, but when he heard that Marshal Jean Baptiste Bernadotte's I Corps had marched through Prussian Ansbach, he made the critical decision to stay and defend Ulm rather than retreat to the south, which would have offered a reasonable opportunity at saving the bulk of his forces. Napoleon had little accurate information about Mack's intentions or maneuvers; he knew that Kienmayer's Corps was sent to Ingolstadt east of the French positions, but his agents greatly exaggerated its size. On 5 October Napoleon ordered Marshal Michel Ney to join Marshals Jean Lannes, Nicolas Jean de Dieu Soult, and Murat in concentrating and crossing the Danube at Donauwörth. The French encirclement, however, was not deep enough to prevent Kienmayer's escape: the French corps did not all arrive at the same place – they instead deployed on a long west-east axis – and the early arrival of Soult and Davout at Donauwörth induced Kienmayer to exercise caution and evasion. Napoleon gradually became more convinced that the Austrians were massed at Ulm and ordered sizeable portions of the French army to concentrate around Donauwörth; on 6 October three French infantry and cavalry corps headed to Donauwörth to seal off Mack's escape route.
Realizing the danger of his position, Mack decided to go on the offensive. On 8 October he commanded the army to concentrate around Günzburg and hoped to strike at Napoleon's lines of communication. Mack instructed Kienmayer to draw Napoleon further east towards Munich and Augsburg. Napoleon did not seriously consider the possibility that Mack would cross the Danube and move away from his central base, but he did realize that seizing the bridges at Günzburg would yield