The battle of Trenton, Christmas Eve, 1776, was the make-or-break operation for the remains of the Continental Army. They had been chased across all of New Jersey, and were discouraged and worn out. If this attack failed, the revolution would not be able to continue, as the fighting men were at the end of their enlistments.
Contrary to popular belief today, the Hessians had not been partying that night; they were exhausted from continual guerilla attacks by the New Jersey militia.