The site of the battle is a wooded height approximately halfway between the villages of Teugn and Hausen in Lower Bavaria, part of modern-day Germany.

Austria's invasion of the Kingdom of Bavaria caught Emperor Napoleon I of France's Franco-German army by surprise.

Though the advance of Archduke Charles's Austrian army was slow, mistakes by Napoleon's subordinate Marshal Louis-Alexandre Berthier placed Davout's corps in great peril.

As Davout withdrew southwest from Regensburg on the south bank of the Danube, Charles tried to intercept the French with three powerful attacking columns.

French reinforcements finally pushed the Austrians off the southern ridge late in the afternoon, and Charles ordered a retreat that night.

At the start, only 15,000 of the best Landwehr formations were added to the field army while the rest were relegated to garrison duty or the reserves.

The I Armeekorps was led by General der Kavallerie Count Heinrich von Bellegarde and numbered 27,653 men.

The I Reserve-Armeekorps was directed by General der Kavallerie Johann I Joseph, Prince of Liechtenstein and counted 18,063 men.

[13] On 9 April 1809, Archduke Charles gave notice to the French ambassador at Munich and Marshal François Joseph Lefebvre that Austria and France were at war.

From Paris, Napoleon ordered Marshal Louis-Alexandre Berthier to form the Armée d'Allemagne (Army of Germany) from French and Allied units located on the Danube front.

Meanwhile, the emperor instructed Oudinot to support Lefebvre, and directed Général de Division Dominique Vandamme's small Württemberg corps to march east from Ingolstadt.

From there, the right column would pass near Eckmühl (Eggmühl) and turn north for Regensburg, where it would rendezvous with General-Major Peter von Vécsey's II Armeekorps brigade.

Attached to this command was General-Major Andreas Schneller's II Reserve-Armeekorps cuirassier brigade[24] and Feldmarschall-Leutnant Karl Friedrich von Lindenau's V Armeekorps infantry division.

Rosenberg advanced toward the hamlet of Dünzling, while Hohenzollern's proposed route went through the villages of Haugen and Saal an der Donau.

Kollowrat's II Armeekorps assembled on the Danube's north bank, opposite Regensburg, which was defended by a small French garrison.

[29] At the beginning of the war, Feldmarschall-Leutnant Franz Jellacic's division was detached from Hiller to capture Munich and provide a link between Bavaria and the Tyrol.

The corps commander also directed one battalion to make a night march in order to secure the all-important Saal defile.

With less than 4,000 troops, Montbrun conducted a brilliant delaying action against IV Armeekorps all day, using the wooded terrain to good advantage.

[33] Rosenberg's corps was weakened early in the campaign by the detachment of Feldmarschall-Leutnant Joseph von Dedovich's division to besiege Passau.

[35] At 9:00 am near Schneidert, three kilometers east of Haugen, General-Major Karl Wilhelm von Stutterheim's IV Armeekorps advance guard brigade brushed against the 12th and 21st Line Infantry of Gudin's division as they marched west.

[40] Far to the southwest at Pfaffenhofen an der Ilm, General Nicolas Oudinot fell on Scheibler's isolated VI Armeekorps detachment with the leading formations of his II Corps.

Feldmarschall-Leutnant Vukassovich quickly deployed two battalions of light infantry, the Peterwardeiner Grenz and the Archduke Charles Legion, and flushed the French from the village, chasing them north.

By the time the French commanders reacted had Vukassovich installed Moritz Liechtenstein's brigade on a wooded ridge approximately halfway between Hausen and Teugn.

)[42] To gain time for Saint-Hilaire's division to deploy out of the marching column, Davout hurled the 2,000 troops of the 3rd Line Infantry Regiment at Vukassovich and Lusignan's 6,000 soldiers and 12 cannon.

Its attack failed to dislodge the Austrians, but it allowed time for the 57th Line Infantry Regiment (called "the Terrible") to organize a second assault.

Davout's chief of staff, Général de Division Jean Dominique Compans, alertly sent the 72nd Line to stop the flanking move.

With their generals displaying front-line leadership, the Austrian attack roared out of the woods and fell on the French troops lining the first ridge.

Saint-Hilaire waved his men forward in a new frontal attack while a horse artillery battery slipped into position unnoticed by the Austrians.

[50] Austrian general officers suffered unusually heavy losses, attesting to "front-line leadership that heretofore had been rare.

This act conceded the victory to Davout, since it gave the French Marshal a clear line of communication with his Bavarian allies.