At sunrise on June 20, 1782, crewmen from a British privateer entered Chatham’s East Harbor and attempted to carry off three unattended local vessels as prizes. Their raid produced Chatham’s principal armed encounter of the American Revolution. An alarm cannon on Watch Hill summoned the town militia, whose members fired from shore and then pursued the raiders in small boats. The British escaped to their offshore vessel, but the inhabitants recovered the threatened craft.

Cape Cod communities lived with maritime danger throughout the Revolution. The Royal Navy controlled much of the surrounding sea, while British and American privateers cruised for merchant shipping. A privateer was privately owned but operated under government authorization to capture enemy property. Prize money encouraged aggressive raids and seizures. Fishing boats and coastal vessels were valuable not only for their cargoes but also because they could be sold, converted to military use, or denied to the enemy.

The Chatham raiders entered the harbor in boats from a privateer waiting outside. They raised British colors on one of the captured vessels and tried to sail away with all three. The alarm gun rapidly transformed civilians into defenders. Under local officers, armed residents gathered along the shore and opened fire. When the largest vessel grounded, the privateers abandoned it and withdrew in their boats. Chatham men launched their own craft and continued the pursuit, firing as they moved toward open water. The attackers reached their ship, but the prizes remained in American hands.

No large armies participated, and casualty accounts are uncertain, yet the action shows how local defense worked late in the war. Towns maintained militia organizations, lookout points, and alarm systems because distant Continental forces could not protect every inlet. Familiarity with shoals and channels gave local mariners an advantage inside the harbor. Their response combined military obligation with defense of the community’s economic survival.

The date is also significant. Cornwallis had surrendered at Yorktown eight months earlier, but Britain and the United States had not yet concluded peace. Naval warfare and privateering continued in 1782, and coastal residents could not assume that the conflict was over. The attempted seizure at Chatham was part of this prolonged final phase.

The marker stands near the harbor landscape rather than at a preserved fortification. Water, shoreline, Watch Hill, and the route to the offshore privateer formed the battlefield. The encounter’s scale should not obscure its meaning. Three working vessels represented substantial property to a small maritime town, and their loss would have harmed local families. Chatham’s defenders used an alarm cannon, shore fire, and rapid pursuit to prevent that loss. Their success preserves a vivid example of ordinary New Englanders meeting the Revolution at their own waterfront.