During the war, the port on the Thames River was a home to many privately owned ships, many of them armed. They preyed upon the British merchant marine and supply ships. These privateer were licensed by the State of Connecticut. By 1781, the largest military structure on the New London side of the river was Fort Trumbull, which was still unfinished and vulnerable to attack. East of the river on Groton Heights, Fort Griswold commanded the harbor and the surrounding territory.
The fort is square with protecting fortifications on the 2 corners. The lower walls were faced with stone and were topped with a barrier of cedar pickets projecting outwards. A tunnel-like passage way led to a covered ditch which ended at a battery for the cannon southwest of the fort. There were barracks for 300 men inside the fort.
Late in the summer, British generals were eager to distract Washington. They decided to create a diversion by attacking an essential northern supply center of New London and destroy the “Rebel pirate ships” in a single blow. The command of this mission was given to the traitor Benedict Arnold. Arnold, being a native of Norwich, knew the area very well.
On September 6, at sunrise, the people of New London were awakened with the news of a large force of British Regulars have landed on both sides of the river’s mouth and were moving up fast. The people could do absolutely nothing but evacuate and flee the town. A number of ships in the harbor were lucky and caught a breeze and escaped upstream. The 800-man detachment that Arnold led were met with no resistance as they were tasked to destroy any of the stockpiles of goods and naval stores. Buildings, wharfs and ships went down in flames. The fire consumed 143 buildings.
Meanwhile, the British force of 800 men landed on the east side of the Thames River was slowed by tangled woodlands and swamplands. A battalion of New Jersey loyalists who were responsible for moving the artillery, could not keep pace with the Regulars who came within striking range of Fort Griswold. The fort was garrisoned with about 150 militia and local men under the command of Col. William Ledyard. He and his officers were expecting reinforcements to come soon. The British commander, Col. Eyre, had sent a flag demanding the surrender of Ft. Griswold. Col. Ledyard declined.
Soon the same demand was sent again and this time Eyre threatened that “If he were to force to storm the fort, no quarter would be given to its defenders”. Col. Ledyard responded the same way as the first demand. Soon the British force began to spread their ranks and advanced to the fort. As they neared the ditch, they were met with artillery bombardment in which many were killed and wounded. Some tried to gain the southwest bastion but were repulsed. Eyre was badly wounded during the assault. Under heavy musket fire, another group removed some pickets and by hand-to-hand combat reached the cannon and turned it against its own men. Another party, lead by Maj. Montgomery, lead a bayonet charge. Montgomery was killed in the charge. A few of the British Regulars made it to the gate and forced it open and marched in. Ledyard ordered his men to cease fire but fighting continued on both sides.
An account of Ledyard’s death varies between the Americans and the British. The American version states that after Ledyard gave up his sword in surrender, he was immediately killed with his own sword and a massacre followed. The British version makes no mention of either the massacre or Ledyard’s death.
The aftermath of the battle, the British troops embarked, leaving behind a small group to lay gunpowder trail from the magazine to the barracks and then torched it. The sabotage failed when a Patriot put the fire out.