The Moche civilization declines after about 700.

The Groton–New London port is a major center of American naval operations, including highly successful privateering operations against British shipping, yet it is poorly protected.

Fort Trumbull on the New London side is little more than a redoubt open on the inland side, while Fort Griswold in Groton is a more substantial fort.

It is roughly square and bastioned, surrounded by a ditch and some outer earthen defenses.

Both are typically garrisoned by small companies of militia, including a few artillerymen, and overall command of the area's defenses is directed by Lieutenant Colonel William Ledyard.

The forts suffer from continuous shortages of provisions and equipment.

Fort Trumbull is unfinished.

Fort Griswold's infrastructure is complete, but it lacks sufficient gunpowder, cannonballs, food, and troops to conduct an effective stand against the British.

In August 1781, Continental Army Major General George Washington had realizesd that there is an opportunity to strike at the British army of Lieutenant General Charles Cornwallis in Virginia.

He had begun moving his forces south from the New York area, using a variety of stratagems to deceive Lieutenant General Sir Henry Clinton, the British Commander-in-Chief and head of the British forces in New York City.

General Clinton realizes on September 2 that he has been deceived.

He is unable to mobilize quickly enough to assist Cornwallis, and is unwilling to detach a large percentage of his forces in the face of the Continental forces that Washington has left around New York.

Clinton decides to launch a raid into Connecticut in an effort to draw Washington's attention.

He only plans it as a raid, but he also believes that New London can be used as a base for further operations into the interior of New England if a permanent British occupation could be established.

He gives Brigadier General Benedict Arnold command of the forces for the raid.

Arnold is an American, a native of Norwich, Connecticut just up the river from New London, who had betrayed his compatriots to join the British the previous September.

The forces assembled by the British are divided into two battalions, numbering about seventeen hundred men.

The first is under Lieutenant Colonel Edmund Eyre, composed of the 40th and 54th Regiments of Foot and a Loyalist provincial regiment of Cortlandt Skinner's New Jersey Volunteers.

The second battalion is under Arnold's command and consists of the 38th Foot and a variety of Loyalist units, including the Loyal American Regiment and Arnold's provincial regiment, known as the American Legion.

The expedition also includes about one hundred Hessian jägers, a small number of artillerymen, three six-pound guns, and a howitzer, all of which are divided among the battalions.

These troops are embarked on transports and sail on September 4 in the company of a fleet of smaller armed ships, led by Commodore John Bazely in the fifth-rate HMS Amphion.

The fleet anchors about thirty miles (forty-eight kilometers) west of New London to make final preparations, and...

...sails for New London late on September 5, intending to make a nighttime landing.

However, contrary winds will prevent the transports from reaching the port until it is already daylight on September 6.

Ledyard, upon receiving the alert, sends a messenger to notify Governor Jonathan Trumbull and local militia leaders of the British arrival, and goes to Fort Griswold to arrange its defenses.

Fort Griswold's guns are fired twice, a signal of enemy approach.

However, one of the British ships fires a third round, changing the meaning of the signal to indicate the arrival of a victorious friend.

This signal confusion leads to delays in mustering militia companies.

The British land on both sides of the mouth of the Thames River at sunrise on September 6, t.

The people of the town can do nothing but evacuate, and several ships in the harbor escape upstream.

The eight hundred-man detachment that Arnold leads in New London meets with no resistance.

The defenders of Fort Trumbull, twenty-three men led by Captain Shapley, fire a single volley, spike the guns, and board  boats to cross the river to Fort Griswold, following orders left by Colonel Ledyard.

Seven of Shapley's men are wounded, and one of the boats is captured; the detachment that Arnold sends to take Fort Trumbull sustains four or five killed or wounded, according to Arnold's account.

Arnold's troops continue into the town where they set about destroying stockpiles of goods and naval stores.

Under the orders given, parts of the town are supposed to be spared, some of which is the property of those secretly loyal to the British, but at least one of the storehouses contains a large quantity of gunpowder, which Arnold evidently had not known.

When it ignites, the resulting explosion sets fire to the surrounding buildings.

The fire is soon uncontrollable and one hundred and forty-three buildings are consumed by flames.

Several ships in the harbor are able to escape upriver when the wind changes.

Meanwhile, Lieutenant Colonel Eyre's force of eight hundred men lands on the east side of the Thames River, but they are slowed by tangled woodlands and swamplands.

The New Jersey Loyalists land after the initial wave of regulars, also delayed by the difficulty in moving the artillery through rough conditions, and they do not participate in the assault.

General Arnold orders Eyre to assault the fort, believing that it will fall easily.

However, upon reaching a prominence from which he can see its defenses, Arnold realizes that the fort is more complete than anticipated and that taking it will not be easy.

One of the reasons for taking the fort is to prevent the escape of boats upriver, and many have already passed beyond the fort; Arnold, therefore, attempts to recall Eyre, but the battle is joined a few minutes before the messenger arrives.

Eyre launches a full-scale assault upon the fort and its roughly one hundred and fifty defenders on the return of the second parley flag.

As the British near the ditch, they are met by a bombardment of grapeshot that kills and wounds many.

This briefly scatters them, but they reform into two units.

Eyre leads one force against the southwest bastion, where American fire repulse the assault, seriously wounding Eyre and several of his officers. (New London historian Frances Manwaring Caulkins will assert that Eyre was mortally wounded, while Benedict Arnold will report that Eyre survived.)

Major William Montgomery leads the second party to an abandoned redoubt just east of the fort.

From there, they move across the ditch and assault the ramparts.

This unit gains the bastion against fierce resistance, but Montgomery is killed by the thrust of a ten-foot pike from Jordan Freeman, a black man who had previously been a slave in service to Colonel Ledyard.

Montgomery's men are finally able to open a gate from inside, and the British force pours into the fort.

Seeing that the fort is penetrated, Colonel Ledyard orders a cease fire and prepares to surrender it to the British.

What happened next is a subject of some controversy.

The most detailed accounts of the event are from American sources and are fairly consistent in what they describe.

According to these accounts, the British continued to fire on the Americans despite Ledyard's signs of surrender, and much of the garrison was consequently either killed or seriously wounded.

British descriptions of the battle ascribe several possible reasons for their behavior.

During the battle, the fort's flag was allegedly shot down at one point, although it was quickly re-raised.

Some of the British attackers claim to have interpreted the event as striking the colors, making a sign of surrender; the British suffered significant casualties when they then approached the fort on that occasion.

They claimed that this led them to disregard Ledyard's legitimate surrender, and they vented their anger over the death and wounding of their commanding officers.

Some other accounts claim that Americans in one part of the fort were unaware that Ledyard had surrendered, and continued to fight, leading the British to also continue fighting, even against those who had surrendered.

There are two black men and one native known to be among the defenders of Fort Griswold.

The black men are Jordan Freeman and Lambo Latham, who both acted heroically in the battle and were killed in action.

Tom Wansuc is a Pequot who was stabbed in the neck with a bayonet.

The massacre at Fort Griswold marks one of the largest tragedies in the history of Groton and Connecticut, and is one of the last British victories in North America before the end of the war.

Damage to New London is substantial; one estimate places the value destroyed at nearly $500,000.

The battle has left nearly one hundred families homeless and had destroyed nine public buildings and much of the town's waterfront.

The state will identify losses in 1792 that totaled more than £61,000, or $200,000 Continental dollars.

Some who lost homes or property will be awarded land in the Western Reserve.

The slaughter at Fort Griswold has left dozens of Americans dead.

The Groton Gazette will report that casualties numbered about one hundred and fifty.

Some survivors have escaped, but others have been taken prisoner.

Benedict Arnold will later issue a report stating that forty-eight British soldiers were killed and one hundred and forty-five wounded.

General Clinton will praise Arnold for his "spirited conduct", but will also complain about the high casualty rate; about twenty-five percent of the troops sent against Fort Griswold had been killed or wounded.

Many British soldiers will blame Arnold for the events at Fort Griswold, even though he had not been in a position to prevent the slaughter.

Arnold will next propose a raiding expedition against Philadelphia, but the surrender of General Charles Cornwallis at Yorktown in late October will end this idea.