A timeline to kick this off
Thurs, 26th December, 1776 – Washington catches Johann Rahl’s Hessians, killing 22, and capturing the remainder. Rahl loses his life in this action.
Mon, 30th December, 1776 – General Howe’s damning report of the Battle of Trenton, indicating that he believed the Hessians to be suffering the after-effects of Christmas merriment, is dispatched to London aboard a British Merchantman. It arrives in London on Wednesday, 22nd January, 1777. [1]
Tues, 31st December, 1776 – General Washington addresses his men, requesting that they remain fighting for him, despite their expiring enlistments, for another 6 weeks. This seems to persuade them at the time.
Thurs, 2nd January, 1777 – General Cornwallis marches from Princeton towards Trenton with 8,000 of his men, leaving behind Col. Mawhood, with 1,200 men of the 17th, 40th and 55th regiments of Foot, the 16th Light Dragoons, and some 6 guns to defend the city.
Cornwallis meets some resistance in the form of skirmishes with Washington’s men, slowing his march somewhat, so that by the time he arrives it is nearly nightfall. Three times he attempts to cross the Assunpink Bridge, but he is forced to call of the attack on the American defences on the other side until the morning.
Washington takes advantage of the frozen ground to move his artillery and approximately 4,500 men, mostly militia, towards Princeton under cover of darkness.
Fri, 3rd January, 1777 - Some of the militia flee at around 2 o’clock in the morning, under the impression that Cornwallis had managed to encircle them.
Following Cornwallis orders to meet him at Assunpink in the morning, Mawhood sets out with the 17th and 55th towards the river, leaving the 40th just outside Princeton, only to find that Washington has come into position parallel to the road he would be taking. Wheeling back to face him, Mawhood meets Brigadier Mercer’s column of militia with the 17th Foot and 16th Light Dragoons in the orchard of one William Clark sending some of the 55th on to Princeton to fetch the 40th. Mercer’s men are quickly defeated with a bayonet charge at about 8 o’clock, the Brigadier himself being unhorsed and brutally bayonetted [2] by the redcoats, some believing him to be Washington himself. Mercer’s second-in-command, Haslet, is killed by a bullet to the head.
Cadwalader’s brigade is the next to arrive, and is just as easily repulsed, and, seeing the Mercer’s men fleeing the field, they too turn to run. At this moment, Washington himself arrives with the Virginia Continentals and Col. Hand’s Rifleman, then rides forward to rally the fleeing militia, calling "Parade with us my brave fellows! There is but a handful of the enemy and we shall have them directly!"
Mawhood withdraws his men slightly, in order to move out of range of Washington’s artillery fire, while Washington orders the Virginians and Riflemen to move to his right, along with Hitchcock’s New England Continentals, who have just arrived. However, in organising the next volley of fire, Washington is shot fatally, through the neck. [3]
Seeing their General fall, most of the militia, only recently prevented from routing, turn tail and run. The 40th and remainder of the 55th return to Clark’s orchard, and break the resistance from the two line regiments. Cadwalader, trying to hold his militia, is overrun and captured by Capt. Leslie of the 17th. [4]
When Cornwallis realises that he has been out-manoeuvred, he sends General Alexander Leslie’s 1,000 men to assist in sweeping the remainders of Washington’s force from the field, and then to bring Mawhood’s men down to meet with the remainder of Cornwallis’ force.
[1] OTL, this report would have probably been sent with the report of the loss at Princeton. The first POD is that the report is sent back on an earlier ship.
[2] OTL, Mercer received multiple (probably seven) stab wounds when he was unhorsed.
[3] The central POD here, is obviously that Washington is slain whilst directing a volley – in OTL, he rode right to the front line, within 30yds of the British, and there is a record of one of his officers, John Fitzgerald, covering his eyes with his hat in fear of seeing the General killed. Following the death of their talismanic commanding officer, many of the men he had persuaded to stay, and all those he had just rallied back, continue to flee.
[4] The third POD is one which I hope will help with my narrative (we’ll see…) Capt. Leslie was, in OTL, killed in the very opening moments of the battle. Here, his luck is interchanged with Washington’s, as it were.