What Happened at the Battle of Princeton?

A mile southwest of Nassau Hall, past the residential streets and the eating clubs on Prospect Avenue, Princeton Battlefield State Park sits as one of the largest preserved Revolutionary War battlefields in the eastern United States. The park is roughly 700 acres of open fields, forests, and reconstructed colonial buildings; it is the landscape on which, in roughly two hours on the morning of January 3, 1777, George Washington's Continental Army defeated a British and Hessian force and turned a war that the Americans had been losing decisively for six months.

The battle is short and unfamiliar to many international visitors. It is overshadowed in popular American memory by Bunker Hill, Saratoga, and Yorktown — the more famous engagements, the ones the high school history textbooks emphasize. But to military historians and to the founders themselves, the Battle of Princeton and the ten-day campaign that produced it (the Battle of Trenton on December 26, 1776, the second Battle of Trenton on January 2, 1777, and the Battle of Princeton on January 3) are recognized as the campaign that saved the American Revolution. Without them, the war ends in early 1777 with British victory and the United States never exists.

This article walks through what happened that morning, why the campaign was so consequential, and how to visit the battlefield today as a stop on a Princeton trip.

The Strategic Situation in December 1776

To understand the battle, you have to understand how badly the Continental Army was doing in late 1776. After early American successes in Boston (March 1776) and the Declaration of Independence (July 1776), the Continental Army had been driven out of New York City in a series of catastrophic defeats during the summer and fall. By November the army was retreating across New Jersey with British and Hessian troops in close pursuit. By December, Washington had crossed the Delaware River into Pennsylvania with about 5,000 starving, frostbitten, and badly equipped soldiers. The British had effectively taken control of New Jersey. New York City was a British military base. Philadelphia, the American capital, was about to be surrounded.

Most importantly, soldiers' enlistments were expiring on December 31, 1776. The Continental Army of January 1, 1777, was projected to consist of about 1,500 soldiers — a force too small to defend Philadelphia or to maintain itself as an independent military. Washington wrote to his brother on December 18 that "the game is pretty near up." The British commanders thought so too. They went into winter quarters across New Jersey on the assumption that the war would resume in the spring with mopping-up operations.

Washington's bet was to attack before the enlistments expired and before the British could regroup. If he could win a victory, he could re-recruit his army. If he could not, the war was over.

The Trenton Strike: December 26

The first move was the famous one. On the night of December 25–26, Washington's army crossed the ice-clogged Delaware River (the iconic Emanuel Leutze painting depicts this crossing, though the painting itself was made nearly 75 years later and contains many factual errors). The army marched through a snowstorm to Trenton, where a Hessian garrison of about 1,500 was wintering in the town. The Continental Army attacked at dawn on December 26 and overwhelmed the Hessians in roughly an hour of fighting. About 900 Hessians were captured. American casualties were extremely light — two Americans died of exposure during the march, none in the actual battle.

The victory was small in military terms but enormous in political terms. American newspapers had been reporting nothing but defeat for six months; suddenly there was a victory. Volunteers began appearing at the army's camps. Some soldiers whose enlistments had expired chose to re-enlist. Washington moved his army back across the Delaware to Pennsylvania, then back across the river again to Trenton on December 30 to consolidate.

By January 2, the situation had complicated. A larger British force under General Charles Cornwallis — about 8,000 troops — had marched south from Princeton and was preparing to attack Washington at Trenton. The Continental Army, now about 5,000 strong, was facing an army nearly twice its size, with the Delaware River at its back, in winter, with no good escape route.

The Night March

On the night of January 2–3, 1777, Washington made one of the most consequential operational decisions of the war. Rather than fight Cornwallis's much larger force at Trenton or attempt to recross the Delaware (which would have signaled retreat and abandoned the recent gains), Washington's army left a small detail to keep campfires burning at the Trenton position to deceive the British, and then marched east overnight on back roads toward Princeton.

The march was about twelve miles, on rough roads, in below-freezing temperatures, with most of the army exhausted from a week of campaigning. The march succeeded in part because the British were fooled — Cornwallis woke on January 3 to find the campfires still burning and the American camp empty.

By dawn on January 3, Washington's army was outside the village of Princeton. A British force of three regiments under Lieutenant Colonel Charles Mawhood, about 1,200 troops, was leaving Princeton on the same road, marching southwest toward Trenton to reinforce Cornwallis. The two armies met on the open farmland that is now Princeton Battlefield State Park.

The Battle Itself

The fighting on January 3 was sharp and brief. The American advance guard, about 350 men under General Hugh Mercer, encountered the British vanguard in an apple orchard on what is now the western edge of the battlefield. The first volley dropped a number of Americans; in the close-range musket fight that followed, Mercer was bayoneted seven times by British soldiers (a British myth at the time held that the Americans had mistaken Mercer for Washington and intended to kill him; Mercer's actual death came nine days later from his wounds).

The American forward line broke. British infantry advanced, and for about fifteen minutes it appeared that the battle was a British victory. The American second line, led by Washington personally, then arrived. Washington rode forward into the open field, riding within thirty paces of the British line, encouraging his troops to stand and return fire. The Americans rallied. The second line and a Pennsylvania militia force flanked the British. After about another fifteen minutes of musket fire, the British force broke and fled — partly toward Princeton, partly back across the fields. About 200 British soldiers retreated to Nassau Hall in town, where they were besieged and eventually surrendered to American artillery.

The whole engagement, from first contact in the orchard to the surrender at Nassau Hall, took about two hours.

American casualties were significant: about 25 killed and 40 wounded. British casualties were roughly 100 killed and 250 captured. The numbers are small by 19th-century standards. The strategic effect was disproportionate.

The Ten Crucial Days

Together, the Battle of Trenton (December 26), the second Battle of Trenton (January 2), and the Battle of Princeton (January 3) make up what historians call the "Ten Crucial Days" of the American Revolution. The campaign produced three American victories, captured nearly 1,500 British and Hessian prisoners, drove British forces out of central New Jersey, restored American military credibility in Europe (where French observers had been on the verge of writing off the rebellion), and re-recruited the Continental Army for 1777.

After Princeton, Washington took the army into winter quarters in Morristown, NJ, where the Continental Army recovered, expanded, and prepared for the year's later campaigns. The Saratoga campaign of fall 1777, which produced the formal French alliance with the Americans, was made possible because the Continental Army existed at all in the spring of 1777 — and it existed because of the ten crucial days.

For an international visitor, the relevance of the Battle of Princeton is that the United States is, in a real sense, the political consequence of about two hours of fighting on the open fields one mile from the university you are visiting. The campus, the institutions, the country — all of it depended on the outcome of this short battle.

Visiting the Battlefield Today

Princeton Battlefield State Park is open to the public year-round. The grounds include:

The Clarke House, an 18th-century farmhouse that served as the field hospital where General Mercer died of his wounds nine days after the battle. The house is restored and open to visitors during certain hours; a small museum inside has artifacts from the battle and information about the Clarke family.

The Mercer Oak, the original tree under which Mercer was wounded, fell during a storm in 2000 after standing as a battlefield landmark for over 200 years. A descendant tree, grown from acorns of the original, now grows in the same spot.

The Ionic Colonnade, a small classical structure on the eastern edge of the battlefield, built in the early 20th century to mark the site. It is a popular photo location and orientation point for self-guided walks.

The open battlefield itself — perhaps the most affecting feature of the park. Unlike Gettysburg or Saratoga, Princeton Battlefield is mostly open farmland, much as it was in 1777. You can walk across the field where the battle was fought. The orchard is gone but the topography is largely the same. Standing at the eastern edge of the field looking west, you are looking across the ground the British forces marched across at dawn.

Self-guided walking trails with informational placards describe the morning's events in sequence. The placards are short, factually accurate, and place the events in time.

Princeton Battlefield Society Visitor Center runs occasional reenactment events, walking tours, and lectures. The society is the volunteer organization that has worked over decades to preserve and expand the battlefield park; their website lists upcoming events.

A reasonable visit is about two hours: an hour walking the battlefield with the placards, a half hour at the Clarke House, and a half hour at the Ionic Colonnade and the surrounding monuments. Combined with the campus visit and a stop at Nassau Hall (which has a direct physical connection to the battle through the bullet hole and the captured cannons), the battlefield gives a full picture of what happened in Princeton on January 3, 1777.

Logistics

The park is at 500 Mercer Road, about a 20-minute walk from Nassau Hall or a five-minute drive. Parking at the park is free. The grounds are open dawn to dusk; the Clarke House and visitor center have published hours that vary seasonally. There is no admission fee.

Spring and fall are the best visit windows; the open fields are striking in October and again in late April. Summer afternoons on the unshaded battlefield can be hot. Winter visits — particularly around the anniversary in early January — have a particular weight to them; the actual battle was fought in temperatures similar to a typical New Jersey January day.

A good combined day-trip from the campus: morning campus tour and Front Campus walk; lunch in Palmer Square; afternoon at Princeton Battlefield State Park; late afternoon tour of Morven Museum and Garden or the Drumthwacket governor's mansion (open to visitors on certain Wednesdays). The whole day knits together the colonial-and-Revolutionary history that the modern university campus is built on top of.