The American commander, Col. Christopher Greene, soon replied: The Americans accepted the challenge, and no quarter should be taken on either side. Fighting commenced at 4 p.m. From the river, 13 galleys of the Pennsylvania Navy immediately bombarded the Hessians with cannon fire, and the soldiers inside Fort Mercer opened up with muskets and 14 cannons of their own. Two battalions and one regiment of Hessian soldiers advanced through the barrage. Their assault was slowed by trees that had been cut down; branches had been sharpened and stacked in a line around the fort. The battle lasted just 75 minutes; when it was over, 377 Hessian soldiers — and just 14 Americans — were dead.

The horror of that afternoon was soon apparent to the archaeologists. From an excavation pit 10 feet wide, 30 feet long and four-and-a-half feet deep, they recovered 14 skulls and numerous other human bones. Mr. Catts believes that the soldiers belonged to the Regiment von Mirbach and that they were at the center of the Hessian formations during the assault. The injuries to one soldier, Mr. Catts said, included “a musket ball in the lower part of his back above where his pelvis should be; a lead canister shot in the middle of his back, where he had no more thoracic vertebra; and then a one-and-a-half-inch iron grapeshot that seems to have taken off his left arm.”