Denonville’s Ill-Fated March on the Senecas

Engraving of Governor General of New France the Marquis de Denonville

On 1 August 1685 Jacques Rene de Brisay, Marquis de Denonville and newly appointed Governor of New France, arrived at Quebec. An experienced military commander, Denonville was considered by his superiors to be one of the finest officers in the French army and the ideal man to deal with the mortal threat that the Five Nations of the Iroquois Confederacy (Cayuga, Mohawk, Oneida, Onondaga and Seneca) posed to the colony.

His predecessor as governor, La Febvre re la Barre, had been recalled to France after his planned assault on the Onondagas in 1684 failed spectacularly: La Barre’s invading force had been decimated by Spanish influenza while en route to the Onondaga homeland, leaving him with no alternative but to accept the Iroquois’ humiliating terms of peace – including their avowed intention to exterminate the Illinois Indians, who were allies of the French.

The Threat to New France

The economy of New France was critically dependent on the profitability of the North American fur trade, specifically beaver pelts. Maintaining harmonious relationships with the native peoples who harvested the pelts and exchanged them for European goods was essential. The fur traders in New France relied on Indian middlemen, particularly the Ottawa nation, to obtain pelts from the more distant tribes to the north and west and transport them to the French trading posts.

The Iroquois were determined to usurp this lucrative middleman role and re-route the flow of furs to their English allies in Albany, but as long as the western tribes believed the French would protect them from the Five Nations, the trade alliance remained intact. However, the La Barre fiasco had caused these tribes to lose faith in French power and promises: during 1686, the Iroquois and English traders succeeded in diverting a significant volume of furs to Albany. At the same time, Iroquois war parties were rampaging along the shores of the St. Lawrence and Richelieu rivers, attacking French forts, killing or making prisoners of settlers and destroying farms and livestock.

Denonville had been directed to confront the Iroquois threat with an iron fist. He concluded that they had to be thoroughly humbled by a display of French strength – a crushing pre-emptive strike against their villages, to be launched in the summer of 1687.

Denonville’s Plan

The homelands of the Five Nations lay to the south of the St. Lawrence River and Lake Ontario, bordered by the Hudson River to the east and Lake Erie to the west. The Mohawks occupied the easternmost section of this territory. Immediately to the west lay the villages of the Oneida and Onondaga peoples. The Cayugas dwelt further west in the Finger Lakes region, while the Senecas guarded the western frontier.

Denonville’s initial plan required two armies: one to attack the Senecas on the Iroquois’ western flank, the other to simultaneously attack the Mohawks on the eastern flank – and to frighten the English at Albany into inaction. After destroying the Seneca and Mohawk villages, the two armies would march on the three central tribes and annihilate them. Denonville soon realized he lacked the manpower to execute this ambitious plan but, believing the risks to the colony demanded action, he settled on a scaled-back scheme: an attack on the Senecas – the most distant, powerful and belligerent of the Five Nations – with the forces at his disposal.

Denonville carefully masked his preparations. The flat-bottomed bateaux that would transport the troops for most of the journey were pre-fabricated at Montreal: the boards to build them were cut to size and then concealed, ready for assembly just prior to departure. The army would need to reprovision at Fort Frontenac at the eastern extreme of Lake Ontario, so supplies were sent there well in advance. To bolster his fighting strength, Denonville directed the commanders of the French posts in the west to assemble a force of coureurs-de-bois and Ottawa warriors at Niagara, where the Niagara River entered Lake Ontario: from there, they would link up with his main force. He also ordered the commanders to enlist warriors from the Illinois nation and march them to the south of the Seneca villages, where they would be positioned to cut off a Seneca retreat – becoming the anvil for Denonville’s hammer.

The Journey to Fort Frontenac

On 13 June 1687, Denonville’s army – 832 Troops de la Marine (independent companies of soldiers recruited in France) and 900 Canadian militia – departed Montreal for Fort Frontenac. The next day, they were joined by 400 allied Indians.

Progress was slow travelling upstream on the turbulent waters of the St. Lawrence. There were several lengthy stretches of rapids that required portages. In these instances, the Troops de la Marine tramped through the wilderness, loaded with supplies, whilre the Canadians dragged the bateaux through the surging currents (300 men suffered leg injuries through these exertions).

The army reached Fort Frontenac on 1 July. The following day, Denonville learned that the Illinois had refused to march against the Senecas, a development that greatly reduced the likelihood of delivering a devastating blow to the enemy. Nonetheless, Denonville judged that delaying the attack until he could redeploy resources to replace the Illinois posed a greater threat to its ultimate success.

The Assault

The invasion force left Fort Frontenac on 4 July and skirted the southern shore of Lake Ontario for several days. Denonville knew the Iroquois were aware of his presence, and sought to conceal his destination for as long as possible by staging numerous feints toward the shore. On 10 July, the troops reached their disembarkation point at Irondequoit Bay, where they were joined in short order by 180 coureurs-de-bois and 400 Ottawa warriors from Niagara.

Leaving 400 men to guard the boats and supplies for the return journey, the combined force set off on a two-day march through the forest in the midsummer heat and humidity. In addition to weapons and ammunition, each man carried provisions for thirteen days on his back. Toward the end of the second day, the army was ambushed by a party of Seneca warriors. After a brief scrimmage in which they sustained several casualties, the badly outnumbered Senecas fled in panic, but were not pursued: the French troops were too exhausted, and their Indian allies were occupied in scalping and butchering their dead enemies.

The following day Denonville advanced on the Seneca villages, only to find them deserted: the tribe had retreated southward unopposed and escaped. The army spent the next ten days burning the longhouse dwellings and the crops in the fields surrounding the villages. Frustrated by his inability to crush the Senecas, Denonville considered marching east to attack the neighbouring Cayugas, but dysentery had broken out among his men. He ordered the army to return to the boats. By 13 August, he was back in Montreal.


Denonville’s attack, though a masterpiece of planning and logistical coordination, failed to achieve its goal. Because the Senecas’ were able to retreat unchecked, they suffered only limited casualties and their fighting strength was not materially impaired. The burned longhouses were soon rebuilt, and the English at Albany were quick to rearm their allies and supply food to replace the destroyed crops. Now the Senecas, and the other nations of the Iroquois Confederacy, lusted for revenge.


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