Following the battle of Abensberg the three Austrian corps retreating in very poor order south easterly towards Landshut, and its bridge over the river Isar, were pursued by Lannes corps [plus Vandamme and Wrede's divisions]. The Austrian commander Hiller, his VI Corps being most intact, tried to make a stand at Landshut but determined attacks by the French plus the arrival of advanced elements of Massena's corps on the south bank of the river caused him to abandon Landshut and continue his retreat southwards.
While the battle of Landshut was being fought Davout and Lefebre's corps were still heavily engaged with the northern half of the Austrian army, reinforced with two fresh corps.

A town on the river Isar in southeastern Bavaria, Germany about 38 miles northeast of Munich [now München]. (Germany)

Austrian Army

Number engaged :

20,000

Casualties :

5,006 (25.03%)

French Army

Number engaged :

10,800

Casualties :

1,575 (14.58%)