The Battle of Millstone, also known as the Battle of Van Nest's Mill, was a skirmish that occurred near the mill of Abraham Van Nest in Weston, New Jersey (near present-day Manville, New Jersey) on January 20, 1777, during the American Revolutionary War. A British foraging party was flanked and driven off by forces composed mostly of New Jersey militia, depriving the British of their wagons and supplies. This action was one of a series of skirmishes known as the Forage War that persisted in northern New Jersey through the first few months of 1777, and it demonstrated that militia companies were capable of putting up a significant fight. After General George Washington's successful movements around the army of Lieutenant General Charles Cornwallis that culminated in the Battle of Princeton, Washington faced the dilemma of being caught between Cornwallis' troops in Trenton and the rest of the British Army at New Brunswick. Rather than make an attempt on the British outpost at New Brunswick with his exhausted troops, Washington moved his army up the Millstone River valley toward Morristown, a place he knew could be strongly fortified and used as winter quarters. Cornwallis and the remaining British and Hessian troops in and around Trenton and Princeton withdrew to New Brunswick to regroup after the battle at Princeton. On January 13, a significant portion of the British army advanced from New Brunswick west to Somerset Court House (present-day Millstone), and remained there for about a week before retreating back to New Brunswick, destroying houses and plundering supplies. During this time, militia companies mustered to assist the Continental Army.

Militia companies to the north were alerted to the British movement early in the day, and some marched for Bound Brook, New Jersey. When reports arrived of the activity at Van Nest's mill, they marched for that place. In all about 400 New Jersey militia and 50 Pennsylvania militia formed under Brigadier General Philemon Dickinson to dispute the British action. While detailed accounts of their movements are sketchy, Dickinson apparently divided his forces, sending one force to meet the front of the British wagon train, while a second moved to flank them. Both of these forces forded one of the rivers, wading in icy water that was waist deep. One successfully surprised the British wagon train in the lane near the mill, before it reached the main road and the bridge toward New Brunswick; their fire struck horses from the first wagon. Archibald Robertson, a British officer who was not part of the expedition, reported that "Lieutenant Colonel Abercromby with 500 men went on a foraging party towards Hillsborough. Part of this Corps was attacked by the Rebels, which has such disorder that 42 wagons were left behind. This stopped the train, scattered the wagon drivers and drove the British to retreat precipitously toward the bridge, leaving their booty behind. Skirmishing continued between American and British forces throughout the winter in the Forage War, since it revolved around the British need for forage for its horses. The American tactics, primarily driven by New Jersey militia commanders but supported by Washington and the Continentals, were so successful that even British foraging parties of 2,000 men came under attack.