When Schwarzenberg and Napoleon clashed at Munich on April 12th, Archduke Charles had his army in the north and east of Bavaria, hoping to cover the approaches there. Following the Battle of Munich, the French wings that had converged there parted, with Massena striking north to seek a passage over the Inn River and Napoleon pursuing Schwarzenberg toward that general's depot at Salzburg.

Charles meanwhile, who had almost made it to Munich personally, spent the following few days dodging French advanced patrols between the Isar and Inn Rivers. There were small engagements at Pfaffenhofen and Detting and then, on the 14, the French drove in Alvinzi's forces at Landshut, forcing them to retreat into the fortress. Through all of the small battles though, the Austrians managed to escape the bulk of their army across the Inn through Aiche and Passau.

Charles is still in the process of concentrating his army at Branau when Marshal Massena's Armee de Norde attacked from both Detting and Aiche.

By nightfall of the 16th, Massena had assembled the 1me Cavalry Corps (Pajol)  and the bulk of Ney's IV Corps  on the battlefield, giving him 27,000 troops.

Archduke Charles is there with two corps: II Korps, under Hiller, is made up of Hungarians and is mostly Insurrection troops but Radetzky's Liebe Garde Korps is a powerful array of Grenadiers and heavy cavalry. He also has the remnants of the Erzhog Karl Legion that was roughly handled at both Herrsching and Munich. This division had belonged to the Army of Schwarzenberg but Charles assigns them to I Korps, which is expected to arrive during the battle. Finally, there is a division of hastily raised militia cavalry that had that day arrived from Salzburg. In total, the Austrians will have more than twice the initial strength of the French.

The Austrians deploy with the Liebegarde in the center, north of the Inn. Erzhog Karl legion is deployed in the village of Stubenberg to anchor the far right. Hiller's II Korps is on the south bank of the river, assigned the task of securing Branau and Waltersdorf.

Massena's small army fields the cavalry on the left and the center will advance to engage the enemy in a straightforward manner.

The aggression of the Austrians is uncharacteristic. Radetsky's grenadiers fairly sprint across the battlefield to slam into the French before they can properly deploy and establish their intervals. When threatened by cavalry, the veterans deftly form square and so a single brigade neutralizes Pajol's corps.

First reinforcements have arrived for the French in the form of the lead elements of V Corps.

Ney's Corps is reeling from the initial aggression of the grenadiers. The Austrians have outpaced their artillery though.

And for an hour or more the grenadiers continue to attack, reaching to the I Cavalry Corps positions and capturing a General of Division. Further stressing Massena's position, the Austrian I Korps has reached Waltersdorf and is bring fire onto the exposed right flank of the French line.

The remainder of V Corps arrived and advances quickly to try to cover the left flank of the French battle line. Austrian reinforcements can be seen to be approaching from Reid. The grenadier attack in the center has begun to stall and brigades that are routed back to behind the gun line are rallied and formed into defensive lines.

On the far left, the light cavalry of Moreau brazenly mixes it up with the heavy cavalry of Radetzky and does not come off entirely badly. 

Ney's Corps, still trying to stabilize against the grenadiers to their front, does not have the resources to face the Grenzers from Hiller's Korps.

With the arrival of Lindenau's Korps, almost the whole of Charles' army is present and has massive numerical superiority. Ney's Corps is stressed toward breaking point but somehow manages to hold the line.

The French cavalry brigades in the center and the Austrian Landwehr cavalry make charge after charge in support of their infantry. As the attack of the grenadiers slackens, Ney is able to commit his rallied troops to the right to oppose the advance of the Hungarian Korps through Waltersdorf.

On the far left of the French line, V Corps' advance is slowed because they are using divisional squares due to the threat of the 6000 Austrian heavy cavalry.

Opposing reinforcements square off to take up the slack as the units in the center begin to separate.

As IV Corps goes on the offensive against Waltersdorf, a large mass of routed Austrians begins to form on the riverbank.

French chasseurs from III Corps manage a breakthrough and are able to ride into the routing, milling masses. Their sabre arms grow weary of the work as four brigades are sent fleeing and swimming for their lives across the Inn.

The fight in the center winds down to consist of long range artillery fire. The French are exhausted and Ney's Corps is incapable of making any more advances but the grenadiers and II Korps do not have time to make another attack against them before nightfall.

In the north, the two fresh corps come to grips and for the few hours remaining before the end of daylight, they exchange bayonet pleasantries.

Massena, though he has a fresh corps possibly coming from Salzburg, cannot ask his shattered IV Corps to fight another day. Reluctantly, he orders the army to withdraw toward Detting. The retreat is made in good order.