The Battle of Chestnut Neck was fought on October 6, 1778 in southern New Jersey during the American Revolutionary War, at Chestnut Neck, a settlement on the Little Egg Harbor River (now known as the Mullica River) near the present-day city of Port Republic, New Jersey, which was used as a base by privateers. The British retrieved some supplies and destroyed others, as well as destroying some residences and other buildings. On September 30, a fleet of nine British ships and transports, under the command of Captain Henry Collins, with 300 British regulars and 100 New Jersey Loyalists, under Captain Patrick Ferguson, sailed from New York, bound for Chestnut Neck. Governor William Livingston learned of their sailing, and sent riders to warn the people. General Washington dispatched Count Kazimierz Pulaski and his Legion to assist the Patriots, although they did not arrive until the day following the battle. Because of bad weather, the British fleet did not arrive off Little Egg Harbor until late in the afternoon of October 5, 1778, and were prevented from getting over the bar.

Knowing the people had been warned and that Count Pulaski was on his way, the British troops made their way up the river to Chestnut Neck as quickly as possible. The troops were put aboard the galleys and armed boats and left at daybreak on October 6, 1778. They were delayed when two boats grounded, and did not reach Chestnut Neck until four o'clock, in heavy fog. They fought against American defenders and retrieved some supplies. Having destroyed any supplies that they could not retrieve, and having received intelligence that Count Pulaski was on his way, they quickly left at noon on October 7, 1778, stopping at the mouth of the Bass River to destroy the salt works and mills of Eli Mathis. They also burnt the houses on his plantation, his home and barns and then rejoined their ships. Although they retrieved some supplies and destroyed others at Chestnut Neck, Ferguson's men were not able to capture any of the American privateers or recapture any of the prize vessels present in the area. After the battle, Chestnut Neck never regained its status as a trade center. Three of the large land owners returned and rebuilt their homes, but the others eventually built new homes in present-day Port Republic.