Wearing the enemy's uniform and impersonating them like that is a war crime, incidentally. It's obviously not as bad as chemical warfare and the like, but it's still amusing to say that they committed a war crime in this battle.
Judging from his fatigue from the start of the chapter, I think this is a rare instance where this isn't the lethal Japanese cold, but instead a proper fever that he's been battling for a few days.