Tactics
Early in the winter, Washington sent out detachments of troops to systematically remove any remaining provisions and livestock from convenient access by the British. General Cornwallis sent out small foraging and raiding parties in January. These were met by larger formations (numbering 300 and up) of American militia companies, sometimes with Continental Army support, that led on occasion to significant casualties. In one early example, Brigadier General Philemon Dickinson mustered 450 militia and drove off a British foraging expedition in the Battle of Millstone on January 20. Washington gave his commanders wide latitude in how to act, issuing commands that they were to be "constantly harassing the enemy", and that they should be aggressive in their tactics. These early successes depended in part on successful intelligence; one British commander reported being met with force "notwithstanding the Orders were given, but a few hours before the Troops moved." Even supply convoys bringing provisions from outside the state to the large garrison at New Brunswick were not immune to the American attacks, where the Raritan River and the roads from Perth Amboy offered opportunities for sniping and raiding. Their difficulties led British commanders to change tactics, attempting to lure these militia units into traps involving larger numbers of British regulars.
But even this was not entirely successful, as wily militia and Continental commanders including Continental Army General William Maxwell used superior knowledge of the geography to set even more elaborate traps. In one encounter in late February, British Colonel Charles Mawhood, thinking he had flanked a party of New Jersey militia, suddenly found his advance force flanked by another, larger force. As they were driven back toward Amboy, more and more Americans appeared, ultimately inflicting about 100 casualties. The elite grenadiers of the 42nd Foot, part of Mawhood's vanguard, were badly mauled in the encounter. A British force of 2,000 was repulsed by Maxwell in another well-organized attack a few weeks later.
The ongoing tensions took their toll on the beleaguered British. Johann Ewald, captain of a company of German jägers (essentially light infantry) who were often on the front lines, observed that "the men have to stay dressed day and night ... the horses constantly saddled", and that "the army would have been gradually destroyed through this foraging". Some forage was provided from New York, but it was never sufficient for the army's needs. As a consequence, the British were forced to provide many supplies from Europe, at great cost and risk to the Royal Navy.
Read more about this topic: Forage War