September 21, 1780

Benedict Arnold commits treason

On September 21, 1780, during the American Revolution, American General Benedict Arnold meets with British Major John Andre to discuss handing over West Point to the British, in return for the promise of a large sum of money and a high position in the British army. The plot was foiled and Arnold, a former American hero, became synonymous with the word “traitor.”

Battle of Quebec: When Benedict Arnold Tried to Invade Canada

The Revolutionary War officer-turned traitor had a brilliant strategy—except that everything went wrong.

Benedict Arnold
Benedict Arnold commanded provincial troops sent against Quebec through the wilderness of Canada.The Library of Congress

Benedict Arnold is now known mostly as a notorious Revolutionary War traitor who secretly tried to sell out the fort at West Point in exchange for a payoff and a commission in the British Army. But except for a few unfortunate twists of fate, Arnold instead might have gone down in history as one of the war’s great heroes. 

Patriot forces under Colonel Arnold and General Richard Montgomery attempted to capture the British-occupied city of Quebec and prompt the province of Quebec to join the rebellion against the British.

It was a visionary strategy, but it didn’t work out that way.

Arnold’s expedition turned into a disastrous defeat, one that nearly cost him his own life and helped stunt his career as an American officer. The botched mission started him on the road to disillusionment and treason. But Arnold’s plan itself actually wasn’t that bad of an idea.

Arnold Persuades George Washington They Needed Canada on Their Side

“The strategy itself was brilliant,” explains Willard Sterne Randall, a professor emeritus of history at Champlain College and author of the 1990 biography Benedict Arnold: Patriot and Traitor, as well as numerous other works on early American history. “Benedict Arnold was a brilliant strategist, but in this case, a terrible tactician.”

Arnold, who before the war had traded with Canadians and still had contacts there, first approached George Washington in the Spring of 1775 to propose an invasion of Canada, according to Joyce Lee Malcolm’s book The Tragedy of Benedict Arnold. Arnold argued that seizing Quebec had huge potential benefits. In addition to depriving the British of a potential staging area for attacking the 13 colonies from the north, Americans envisioned that French Canadians might seize the opportunity to rise up against the British and join in the fight for independence. 

In a June 1775 letter to the Continental Congress, Arnold also wrote that taking Quebec would deprive the British of the lucrative fur trade and secure “an inexhaustible granary” of Canadian wheat to feed Americans.

Benedict Arnold's Journal
Benedict Arnold’s journal which highlighted his travels in Quebec, circa 1775.Suzi Piker/Portland Press Herald/Getty Images

Washington probably didn’t need that much convincing, because from the American viewpoint, Canada seemed ripe for the picking. The British only had 775 troops in the entire country, according to Randall, and the then-capital of Quebec City was guarded by fewer than 300 soldiers.

In his letter to the Continental Congress, Arnold envisioned a straightforward march to Montreal. But as detailed in Thomas A. Desjardin’s book Through a Howling Wilderness, Washington opted instead to go with a complicated, two-pronged attack. One part of the force would head up through New York toward Montreal, while to the east, a second 1,050-man contingent led by Arnold would make their way through the Maine wilderness to Quebec City, with the aim of catching the British by surprise.

The Expedition to Quebec Was Grueling

It might have worked, except that as Randall notes, “everything went wrong.” Because of a holdup in getting pay for the men, the expedition got off to a late start in September. The map obtained by Arnold was inaccurate, and the route turned out to be far longer and more arduous than he had envisioned. 

Worse yet, Randall says, the Maine shipbuilder hired by the expedition secretly was a British loyalist, and he deliberately used heavy green wood and left out the caulking, so that the barges laden with supplies soon sank in the Kennebec River. After a brutal hurricane wiped out more of their provisions and equipment, many of Arnold’s men deserted and headed back home. By the time Arnold finally got to his destination in November, he had only 675 starving, poorly armed soldiers left, according to Malcolm’s account.

Meanwhile, Sir Guy Carleton, the skillful, savvy British commander in Canada, had rushed to Quebec City. By the time Arnold got there, British reinforcements—battle-hardened Scottish veterans of the French and Indian War—had arrived to bolster the defenses.

“If Arnold had gotten to Quebec three days earlier, it might have worked,” Randall explains. “He almost pulled it off.”

The city of Quebec and the Saint Laurence River at the time of the attack by United States Forces, circa 1775.
The city of Quebec and the Saint Laurence River at the time of the attack by United States Forces, circa 1775.Fotosearch/Getty Images

A New Year’s Eve Attack in a Blizzard Fizzles

Instead, after threatening to inflict “every severity” upon Quebec unless it surrendered, Arnold had to sit and wait for additional troops led by Maj. Gen. Montgomery to arrive. As this 1990 article by Randall details, the Americans finally launched their assault on Quebec City on New Year’s Eve in a blinding blizzard, and it quickly turned into a disaster.

A single volley of cannon fire killed Montgomery and most of his officers, and Arnold was severely wounded in the leg by a rifle shot and had to be dragged off the field. (Here is Carleton’s account of the battle.) Most of the American force was killed, wounded or captured, so that of the 300 men who’d survived the journey with Arnold to Quebec, only 100 were left.

Copy of a letter from General CARLETON to General HOWE, dated Quebec, Jan. 12, 1776


The 5th of December Mr. Montgomery took post at St. Croix, within less than two miles of Quebec, with some field artillery; his heavy cannon were landed at Caprouge; at the same time Arnold’s party took possession of the other avenues leading to the town, and prevented all communication with the country.

The 7th a woman stole into town with letters, addressed to the principal merchants, and promising them great indulgence in case of their compliance.

Inclosed was a letter to me in very extraordinary language, and a summons to deliver up the town; the messenger was sent to prison for a few days, and drummed out.

To give more efficacy to these letters, five small mortars were brought to St. Rock’s, and a battery of five cannon and one howitzer raised upon the heights, within about seven hundred yards of the walls.

Soon after Arnold appeared with a white flag, and said he had letter for me, but was refused admittance, and ordered to carry back his letter.

After every preparatory stratagem had been used to intimidate our wretched garrison, as Mr. Montgomery was pleased to call it, an assault was given the 31st of December, between four and five in the morning, during a snow storm from the north-east.

The alarm was general: from the side of the river St. Lawrence, along the fortified front, round to the bason, every part seemed equally threatened.

Two real attacks took place upon the Lower Town: one under Cape Diamond, led by Mr. Montgomery, the other by Mr. Arnold, upon the part called the Saut au Matelôt.

This at first met with some success, but in the end was stopped.

A sally from the Upper Town under captain LAWS attacked their rear, and sent in many prisoners, captain M’DOUGAL afterwards reinforced this party, and followed the rebels into the post they had taken.

Thus Mr. Arnold’s corps, himself and a few others excepted, who were wounded and carried off early, were completely ruined. They were caught as it were in a trap; we brought in their five mortars and one cannon.

The other attack was soon repulsed with slaughter. Mr. Montgomery was left among the dead.

The rebels have on this assault between six and seven hundred men, and between forty and fifty officers, killed, wounded, and taken prisoners.

We had only one lieutenant of the Navy doing duty as a captain in the garrison, and four rank and file killed, and thirteen rank and file wounded, two of the latter are since dead.

You will be pleased to transmit a copy of my letter to the secretary of state, by the first opportunity, for his majesty’s information, &c.


The brutal defeat “struck an amazing panick” among the Americans, as Arnold conceded in a dispatch to Washington a few weeks later. But to Arnold’s credit, he didn’t give up. Along with the tattered remainder of his forces, he cleverly kept up the siege, moving a single cannon around and firing at the fort to create the illusion that he had more artillery, according to Randall. In that fashion, Arnold held out until spring, when reinforcements from New England arrived, and he was ordered to return home.

“Arnold was superseded and pushed aside,” Randall says. It was the start of a pattern, in which his field experience and bravery was disregarded and he was repeatedly passed over in favor of other officers. “This was the beginning of his dilemma about which side to be on.”

Eventually, the arrival of a British fleet carrying 10,000 British regulars and German mercenaries in May 1776 forced the Americans to retreat for good.

The Quebec Act Sealed French Canadians’ Allegiance to the British

The French Canadian uprising that Arnold and others had hoped for never materialized, thanks to the property and religious rights that the British had conferred in the Quebec Act of 1774. “The French Canadians were Catholics, and they’d just been given legal status by the British,” Randall explains. “They saw the American invasion as a Protestant invasion.”

Despite his failure to take Quebec, Arnold eventually did manage to prevent the British from attacking from the north. In October 1776, he hastily put together a small fleet of ships that met Carleton’s invading force in the Battle of Valcour Island, and put up such fierce resistance that the British had to turn back. Four years later, Arnold would switch sides—and cement his legacy as one of the most infamous traitors in history.

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