Kammala jumla mai zuwa: A farkon Yaƙin Haɗin Gwiwa na Biyar, Deroy ya ba da umarnin Rukunin 1 ga Yarima Ludwig na Bavaria kuma ya ɗauki nauyin Rukunin na 3 a cikin VII Corps. Wannan rukunin ya kunshi 5th, 9th, 10th, da 14th Infantry Regiments, da 5th da 7th Light Battalions, da "Taxis" Dragoons da "Bubenhoven" Chevau-légers, da kuma kayan aiki 18. Bayan mamayewar Austriya, Deroy ya mamaye yammacin Kogin Isar da ke gaban Landshut a ranar 16 ga Afrilu 1809. A cikin wani ɗan gajeren lokaci, kowane bangare ya rasa mutane 150 zuwa 200 da aka kashe da kuma rauni. Bayan wani rukunin Austrian ya haye sama a Moosburg, sai ya koma baya ta hanyar Pfeffenhausen zuwa Siegenburg. A karkashin jagorancin Marshal François Joseph Lefebvre, Deroy ya kasance a wurin amma ba a shiga cikin
Yaƙin Abensberg a ranar 20 ga Afrilu.