High Quality Content by WIKIPEDIA articles! The Battle of Iron Works Hill, also known as the Battle of Mount Holly, was a series of minor skirmishes that took place on December 22 and 23, 1776, during the American War of Independence. They took place in Mount Holly, New Jersey, between an American force mostly composed of colonial militia under Colonel Samuel Griffin and a force of 2,000 Hessian mercenaries and British Army regulars under Carl von Donop.