Pay attention:
I didn’t say they were drunk. I said they failed to post proper security. From the very next sentence on your linked site:
…a crucial decision was made not to send out a patrol along the river…
Same page, next paragraph:
Despite the noise of the battle, the Hessians had trouble waking up their commander.
From this site:
Rall was ordered to build field works needed to defend the town, but did not. Rall told one of his officers who wanted to build redoubts-“Let them come! We want no trenches! We’ll use the bayonet!”
<snip>In Trenton, Hessian Major Dechow decided because of the severe storm not to send out the normal predawn patrol, including 2 cannon, to sweep the area for signs of the enemy. Though the storm cause extreme misery for the troops, it allowed them to approach undetected.
At 8 AM Washington’s party inquires of a man chopping wood where the Hessian sentries are, just outside of Trenton. He points to a nearby house, and the Hessians pore out and begin to open fire. The battle of Trenton is on.
No fortifications, and the sentries were inside, allowing Washington to approach unnoticed and unmollested. Without patrols, early detection of the advance was impossible. Crappy security.
And why was the Hessian commander so hard to awake?
Maybe because he stayed up too late the night before?
Colonel Johann Raul, Commanding Officer of the Hessian troops, still dazed from his holiday celebrations, raged up and down King and Queen streets, bravely trying to rally his men.
From the first site I linked to:
The Hessians in Trenton were in an exposed position, and it was known that they would heartily celebrate Christmas on the night of Dec. 25 th. Washington decided on a predawn attack on the 26 th, while the troops and officers were tired, and hopefully some suffering hangovers. It is a misconception that the Hessians were expected to be drunk. Some of the officers might have been expected to party late into the night, not the troops.
<snip>The Hessians are caught completely unprepared. Col. Rall, who was up late at night, is slow to awaken and dress.
So: I’ll say it again: If you want to spend the winter in New Jersey, Don’t let your mercenaries indulge in predictable celebrations without first establishing decent security.
The combination of crappy security and lack of effective leadership early in the battle cost Trenton, and the success resurrected the almost moribund rebel army by finally giving it a victory. Without the victory at Trenton, and the spirited action at Princeton a few days later (where Conwallis’ rearguard took a savage mauling before the rebels called it a day), the revolution would have failed that winter. As it was, save for a line from Perth Amboy to New Brunswick, the British were forced to abandon New Jersey, and Washington’s army stayed intact. The French, emboldened, released supplies to the Americans while the English government started losing support for the war.
As for the behavior of the British and Hessians towards New Jersians, before the attack at Trenton:
The militia showed up in disgustingly small numbers. Most men stayed home to protect their families from the advancing invaders, moving possessions out of the way of the British and Hessians. The British and Hessians destroyed Jersey homes, farms and possessions wantonly, and saw little difference between loyalist and rebel, treating most the same.
The result of said poor behavior:
Still everything was not going all the right way for the British. The Jersey men, while not joining Washington, had not reacted passively to being invaded, and the poor behavior of the British and Hessian troops enraged many. Ambushes of British patrols became a standard tactic. Morris county had several units of militia assembled, with some Continental troops, and more troops were around Paramus in the Northeast.
New Jersey irregular troops, acting in small groups, uncoordinated, and fueled by anger at the horrible plundering by both the Hessians and British, raided the enemy to capture supplies, ambushed patrols, harassed communications and movement. On Dec. 18 th, General Grant, under Cornwallis in New Brunswick, ordered that nothing belonging to the army, even officers, leave New Brunswick with out an escort. The local men of New Jersey couldn’t seriously hurt the British, but they could make them cautious, and reduce their ability to get information by patrolling.