It was not one particular person that initiated the attack, and no French commander allowed it. The British and American troops had surrendered and agreed to terms of parole back to Fort Edward off the Hudson river. Marquis de Montcalm had a large war party of Native Americans, some stretching from far west, which some of the party attacked the retreating British and American soldiers.

George Bartman wrote of it in his letters

​

[To Gabriel Christie. Fort Edward August 11th, 1757]

I am to acquaint you that notwithstanding the Terms of Capitulation that our Troops made at Fort Wm. Henry, which that they were to march out with all the Honors of War, the Indians of the Enemy, (and you may imagine not without the connivance of the French) fell upon them upon setting out yesterday with their spears...

Col. Monro, Col . Young and several other officers and soldiers remain there under the protection of the French till they can come off safely, if safely there can be with such violators of solemn Treaties.

Bartman has a bit of resentment towards the French, blaming them for the massacre and the breaking of trust a surrendering army has towards the captors. Bartman was the aide to camp for General Webb at Fort Edward, so he received the information secondhand and was not there to witness it. One of his letters that he sent to Munro was intercepted and brought to Montcalm. James Furnis, a witness of it, wrote a similar resentful look on the French during the surrender and massacre. On the morning of August 9th, the Native Americans had attacked and plundered the fort while terms were being deliberated between the leaders.

The Marquis de Montcalm signifieing [sic] that the Savages not satisfied with the plunder that they got in the morning, intended to attack us on the march, and that it was more advisable to remain until the Morning, when we should have an Escort of Four Hundred and Fifty men.

And on the tenth of August he described:

On the 10th early in the Morning when we were preparing to march, the Savages surrounded us, took my Horses which I had given to carry off the Gun, got over the Breast Work, and began to plunder. At all Events the French Troops who we thought were sent to protect us, were of no Assistance, and advised giving up our Effects rather than dispute with the Savages who would not be satisfied until they had got all the Baggage, this 'tho contrary to the Capitulation (to prevent worse Consequences) was complied with, as the Officers, and Soldiers immediately delivered every Thing up to them, except their Arms and the Clouths on our Backs, which we hoped they would suffer us to carry off. Instead of which they took our Hats, and Swords from us, and began to strip us, on which it was thought proper to march out as soon as possible, the Savages [having] taken the Drums, Halberds, and even the Firelocks from the Soldiers. This unexpected Treatment so contrary to the Terms of the Capitulation, surprized us much, and struck so great a Panick into the Troops, who knew not where it would end, that all Efforts proved ineffectual to prevent their runing away in a very confused and irregular Manner, which gave the Savages an Opportunity of scalping many who were so unlucky to be in the rear or made the least Resistance. The sick and wounded felt the first Stroke of their Bar barity whom they scalped before they could get out of the Breast Work. The Savages pursued about four Miles, and made several Prisoners, amongst whom I was one, at three Miles Distance, by two of them carried back towards Fort William Henry, but was luckily retaken by a French Guard, who sent an Officer and Twenty Men with me into the Fort, where I found Lieut. Colonel Munro, and several Officers, some of which had been made Prisoners, and others had surrendered themselves to a French Post about a Mile from the Fort to protect them from the Cruelty of the Savages.

British forces did not publish official reports of the massacre at all after the battle. Some leaders sent letters to each other but no official document of it. John Campbell, the Fourth Earl of Loudoun did not denounce the French nor really blame them for what happened. Montcalm did deliver the soldiers safely back to British territory after the dust settled a year later. It would remind the people of the British defeat and not a strategy Loudoun wanted to attempt.

The rogue elements of the Native American War party under Montcalm's army started the attack. Montcalm had over thirty different tribes in the war party and had promised prizes should they join him. They expected something different than a siege to turn into surrender and then parole. During the siege they fired at the British forces who hid behind cover and could not get closer until the siege work did. The warriors would have to wait. Then on the 8th, Montcalm discussed with the war chiefs his plan to capture the British and allow them passage. Most war chiefs understood, and some did not understand or agree. The fact that Montcalm urged the British forces to leave during the night meant that he did not have control he would have liked over the Native Americans and possibly cared for their safety. Less than 300 of the 2,300 would be captured or killed, suggesting that not all the Native American warriors participated. Montcalm agreed to the terms that the British soldiers would be protected on their way to Fort Edward and did ultimately attempt to stop the massacre within his power (and safety). Being that the French followed the Honors of War, the attack would not have come from their leadership - even if some of the officers did not lend a helping hand to the British under attack by the Native Americans.

​

Sources:

William S. Ewing and James Furnis. An Eyewitness Account by James Furnis of the Surrender of Fort William Henry, August 1757. New York History 42, no 3. July 1961. Pp. 307-316.

John Shultz. The Siege of Fort William Henry: The Letters of George Bartman. Huntington Library Quarterly, 12 no 4. August 1949. Pp. 415-125