The siege of Fort Stanwix (also known as Fort Schuyler) began on August 2, 1777, and ended on August 22, 1777. Fort Stanwix, at the western end of the Mohawk River Valley, was a primary defense point for the Continental Army against the British and Indigenous forces aligned against them during the American Revolutionary War. The fort was occupied by Continental Army forces from New York and Massachusetts under the command of Colonel Peter Gansevoort. The besieging force was composed of British regulars, Loyalist soldiers, Hessians, and Indigenous warriors, under the command of Brigadier General Barry St. Leger. St. Leger's expedition was a diversion in support of Lieutenant General John Burgoyne's campaign to take control of the Hudson River Valley to the east.

One attempt at relief was thwarted early in the siege when a force of New York militia under Brigadier General Nicholas Herkimer was ambushed on August 6 at the Battle of Oriskany by a large detachment of St. Leger's forces. While the battle did not involve the fort's garrison, some of its occupants sortied and plundered the nearly empty Indigenous and Loyalist camps, which was a blow to the morale of St. Leger's Indigenous allies. The siege was finally broken when American reinforcements under the command of Major General Benedict Arnold approached, and Arnold used a ruse to convince the besiegers that he had a much larger force. This misinformation, combined with the departure of many of the Indigenous warriors, led St. Leger to abandon the effort and withdraw.

St. Leger's failure to advance on Albany contributed to Burgoyne's surrender following the Battles of Saratoga in October 1777. Although St. Leger reached Fort Ticonderoga with some of his forces in late September, he was too late to aid Burgoyne.

Background Fort Stanwix occupied a strategic western portage known as the Oneida Carrying Place (site of modern Rome, New York) between the Mohawk River, which flowed southeast to the Hudson River, and Wood Creek, whose waters ultimately led to Lake Ontario. Built by the British in 1758 during the French and Indian War on the only dry ground in the area, the fort had fallen into disrepair. When the American Revolutionary War widened in 1776 to include the frontier areas between New York and the Province of Quebec, the site again became strategically important.Nickerson (1967), p. 197

British Colonial Secretary Lord Germain and General John Burgoyne developed a plan for gaining control of the Hudson River valley that included an expedition that King George III described as a "diversion on the Mohawk River".Nickerson (1967), p. 90 In March 1777 Germain issued orders assigning the expedition to Lieutenant Colonel Barry St. Leger, an experienced frontier fighter who had served in the French and Indian War.Nickerson (1967), p. 92

Forces assemble In April 1777, Continental Army Major General Philip Schuyler ordered the 3rd New York Regiment under the command of Colonel Peter Gansevoort to occupy and rehabilitate Fort Stanwix as a defense against British and Indigenous incursions from Quebec. Arriving in May, they immediately began working on the fort's defenses. Although officially renamed Fort Schuyler, it was still widely known by its original name. Warnings from the Oneida that the British were planning an expedition were confirmed by mid-July, spurring the pace of the work.Pancake (1977), p. 139Nester (2004), p. 170 In early July, Gansevoort reported on the state of affairs to Schuyler, noting that provisions and ammunition were in short supply. Schuyler ordered additional supplies sent to the fort on July 8.Scott (1927), pp. 138, 166 Later that month the 3rd New York were joined by a 150 man detachment of the 9th Massachusetts Regiment.Watt and Morrison (2003) p. 104

St. Leger, who was brevetted a brigadier general for the expedition, assembled a diverse force consisting of about 240 British regulars from the 8th Regiment of Foot, 34th Regiment of Foot and the Royal Artillery, 250 Loyalists from the King's Royal Regiment of New York (also known as the Royal Yorkers), 90 jäger from Hesse-Hanau, and 50 Canadien laborers.Watt and Morrison (2003), p. 17 His artillery consisted of two six-pound pieces, two three-pounders and four coehorn mortars. He expected these to be adequate for the taking of a dilapidated fort with about 60 defenders, which was the latest intelligence he had when the expedition left Lachine, near Montreal, on June 26.Pancake (1977), p. 140Nickerson (1967), pp. 195–197

St. Leger first learned that the Americans had occupied Fort Stanwix in force when prisoners captured from its garrison were brought to him on the St. Lawrence River.Nickerson (1967), p. 198 He learned from the prisoners that the fort had been repaired and was "garrisoned by upwards of 600 men" and that "the rebels are expecting us, and are acquainted with our strength and route".Pancake (1977), p. 141 Daniel Claus, a British Indian Department superintendent accompanying the expedition, convinced St. Leger to proceed to Oswego on Lake Ontario rather than ascend the Salmon River as originally planned. They arrived at Oswego on July 25, where about 100 Indian Department rangers from Fort Niagara led by deputy superintendent John Butler joined the expedition. Also at Oswego were Joseph Brant with his Loyalist volunteers and a large contingent of Mohawk warriors.

In total about 800 Indigenous warriors joined St. Leger's expedition. Many were Seneca led by Cornplanter and Sayenqueraghta, but there were also warriors from the Cayuga, the Onondaga, the Mississaugas, and from the Upper Great Lakes area.Nester (2004), p. 169Watt and Morrison (2003), p. 18

The expedition ascended the Oswego and Oneida rivers to Oneida Lake, then followed the north shore of the lake to Wood Creek. Wood Creek had been blocked by the Stanwix defenders just a week earlier by felling trees across the creek which slowed St. Leger's forces and forced then to rebuild an old military road in order to reach the fort.

Shortly after leaving Oswego, a report reached St. Leger that more supplies for the fort were en route via a convoy of bateaux on the Mohawk River. St. Leger immediately dispatched Lieutenant Henry Bird and 30 men from the 8th Regiment to intercept those supplies. Bird was later joined by Brant with his volunteers and the Mohawk.Watt (2002), p. 126

Bird and Brant's arrival at the lower landing near the fort early on August 2 was too late.Luzader (2008), p. 127 The supply convoy, which was accompanied by 100 men from the 9th Massachusetts Regiment, had arrived and been unloaded. Bird and Brant were able to capture the convoy's bateaux captain, however, the supplies and Massachusetts soldiers safely reached the fort.Scott (1927), p. 175

Siege begins

St. Leger arrived at Fort Stanwix on the evening of August 2 with the regulars from the 8th and 34th regiments, the jägers, and a company of the Royal Yorkers. The Canadiens, many of the Indian Department rangers, and the rest of the Royal Yorkers were tasked with clearing Wood Creek and the Oneida Carry, which the Americans had blocked with fallen trees.Watt (2002), p. 127

St. Leger's artillery and stores were held up by the same tactic used to slow down Burgoyne's army after the surrender of Fort Ticonderoga. Earlier, Gansevoort had his men systematically fell trees across the Oneida Carry, creating abatises, and St. Leger needed to clear the path before his artillery could proceed. This work took several days and, as a result, the arrival of the artillery was delayed.Glatthaar (2006), p. 158

On the afternoon of August 3, St. Leger paraded his troops, including the Mohawk in their war paint, in view of the fort. He then sent Indian Department Captain Gilbert Tice under a flag of truce with a proclamation authored by Major General Burgoyne. Gansevoort declined to respond, however, Tice was able to gather valuable intelligence about the fort's defenses.Watt (2002) pp. 128–130

Construction of breastworks began the following day. Jägers and Indigenous snipers began to harass the fort's defenders, killing one and wounding several.

On August 5, the main body of Seneca and Cayuga warriors arrived. The same day, Brant received word from his sister, Molly, who was living at Canajoharie, that an American relief column was marching up the Mohawk Valley. Upon receiving the news from Brant, St. Leger immediately dispatched Lieutenant Colonel Sir John Johnson with a company of his Royal Yorkers, Brant with his volunteers, Butler with a detachment of rangers, a detachment of jägers, and several hundred Indigenous warriors to block the American advance.Watt (2002), p. 134

Oriskany

The Tryon County Committee of Safety received news of St. Leger's movements on July 30 and began to assemble reinforcements. On August 4, about 800 men from the Tryon County militia were mustered at Fort Dayton (near modern Herkimer, New York) by Brigadier General Nicholas Herkimer, the committee chairman.Pancake (1977), p. 142 By late the next day Herkimer's column had arrived within of Fort Stanwix where they were joined by about 60 Oneida led by Han Yerry Tewahangarahken.

In planning their ambush, Johnson and Butler deferred to Brant, Cornplanter and Sayenqueraghta.Watt (2002) p. 157 On August 6, at the bloody confrontation near Oriskany Creek, the Tryon militia suffered catastrophic casualties, including Herkimer, who received a serious wound to the leg. In a battle that lasted several hours, roughly half of Herkimer's men were killed or captured. St. Leger's Indigenous allies also suffered significant casualties.Watt (2002) pp. 316–320

Late in the afternoon St. Leger's detachment withdrew back towards Fort Stanwix. Herkimer (who eventually died of his wounds) and the surviving militia also retreated rather than continue their advance.

The confrontation came at a cost to St. Leger. Gansevoort's besieged troops took advantage of the absence of a sizable part of St. Leger's force to make a sortie, in which Gansevoort's second-in-command, Lieutenant Colonel Marinus Willett, led 250 men out and looted the nearly empty Indigenous and Royal Yorkers camps of "several wagon-loads of spoils",Pancake (1977), p. 144 including Johnson's personal papers and orderly book, a British flag, four camp colours, and a letter the British had intercepted from Gansevoort's fiancée.Watt (2002), p. 191 The story about recovering actual wagon loads of materials is probably untrue. It likely dates to a memoir by Marinus Willett written late in his life. No contemporaneous accounts of the sortie, including Willett's earlier journals, mention the need for wagons.Scott (1927), p. 195

When the Indigenous warriors and Royal Yorkers returned from Oriskany they arrived at camps that had been stripped of much, including blankets, kettles and personal belongings. Combined with the fact that the battle at Oriskany had resulted in many Indigenous casualties, this greatly upset the Seneca and Cayuga. They had been told that the regulars and the Loyalists, who had thus far fought relatively little, would do most of the fighting.Nickerson (1967), pp. 269–270 This breach of trust damaged relations between St. Leger and his Indigenous allies, and became instrumental in the eventual failure of the siege.Pancake (1977), p. 145

Siege continues

Siege operations began in earnest following the arrival of the British artillery. The regulars, the six-pounders and the coehorns were positioned on a low rise north of the fort, while most of St. Leger's Indigenous allies and the Royal Yorkers were positioned to the south with the three-pounders.Nickerson (1967), p. 200