Thanks to a Christmas party, the entire garrison was drunk on Jersey Lightning, as applejack was called in that time. Rall was playing cards when the paper was handed to him. Drunk and having higher priorities (his bet on this hand), Rall looked at the paper, saw it was in English and crumpled it up, putting it in his pocket.
When Rall, dying, was laid out in the church in Trenton, the paper was found in his pocket, obviously unread.