Good piece. I really dig this stuff. A few notes:
I think rather (and may be wrong) that Washington actually reoccupied Trenton on December 30, because most of his men's enlistments were due to expire on the 31st. Washington himself pleaded with each regiment to stay for another six weeks, as a favor to him. More than two-thirds reenlisted and remembered the day well years later when they applied for their pensions.
there was no regular American army, just a militia made up of civilians; and most of them were farmers. Naturally, they were not used to long campaigns or battles with British Regulars.
The men who made up the militias were not just simple country farmers. They were men who may not have been polished or organized, but many had proved their worth against other armies in overseas campaigns. New England men had a particular attitude to war: they thought it was terrible but necessary at times, and were emotionally hardened and resolute when they had to fight.