The attack begins well as the central Austrian V Corps guarding Abensberg give way to the French advance.

Napoleon, however, is working under false assumptions that make his goals difficult to achieve.

Massena's advance towards Landshut requires too much time, permitting Hiller to escape south over the Isar.

The Danube bridge that provides easy access to Regensburg and the east bank has not been demolished, allowing the Austrians to transfer themselves across the river and rendering futile French hopes for the complete destruction of the enemy.

On the 20th, the Austrians suffer ten thousand casualties, lose thirty guns, six hundred caissons, and seven thousand other vehicles, but are still a potent fighting force.

Later in the evening, Napoleon realizes that the day's fighting has only involved two Austrian corps.

Charles still has a good chance of escaping east over Straubing if he wishes.