Rubuta ci gaba ga wannan sakin layi - A cikin 1800, an tura Loison zuwa Rundunar Sojoji ta Tsaro don ya jagoranci wani rukuni na 5,300 kuma ya tsallake Babban St Bernard Pass tare da Napoleon. Ya ji rauni ya jagoranci wani harin da aka yi a kan Fort Bard a ranar 25 ga Mayu, 1800. Da sauri ya farfado, ya jagoranci rukunin sa a cikin Guillaume Philibert Duhesme na rundunar a cikin mayar da umarnin Josef Philipp Vukassovich. Ya rasa yaƙin Marengo
saboda mutanensa sun shagaltu da kama Milan da Cremona, yayin da suke bin Austrians zuwa gabas.