Ka kammala wannan jumla: Gwanin sojan nasa ya bunƙasa a lokacin yaƙe-yaƙe na Napoleon. A lokacin yakin 1805, Yermolov ya yi aiki a baya da kuma masu tsaron gaba kuma ya bambanta kansa a Amstetten da
Ƙasar Ostirlitz. Don ayyukansa, an daukaka shi zuwa colonel a ranar 16 ga Yuli 1806. A shekara mai zuwa, ya shiga cikin yaƙin a Poland, yana aiki a cikin masu gadi na Yarima Bagration. Ya bambanta kansa yana jagorantar kamfanin bindigogi a cikin ayyukan baya da yawa yayin koma baya zuwa Landsberg da kuma a yakin Eylau. A watan Yunin 1807, Yermolov ya umurci dakarun dakarun dakarun doki a cikin ayyukan Guttstadt, Deppen, Heilsberg da Friedland, an ba shi lambar yabo ta St. George (na uku na aji, 7 ga Satumba 1807). An ci gaba da shi zuwa babban janar a ranar 28 ga Maris 1808 kuma an nada shi mai kula da kamfanonin doki. A farkon 1809, ya binciki kamfanonin bindigogi na Sojojin Danube. Kodayake sashinsa ya shiga cikin kamfen na 1809 da Austria, Yermolov ya ba da umarnin ajiyar a Volhynia da Podolsk gubernias, inda ya kasance na shekaru biyu masu zuwa. A 1811, ya dauki umurnin mai gadi artillery kamfanin da kuma a 1812, ya zama shugaban ma'aikatan na 1st Western Army.