 A turning point came in 1777 when British forces invaded New York from Canada and laid siege to Patriots in Fort Stanwix . In August , when Brant learned that a large body of Patriot militia was on its way to relieve the fort , she sent Mohawk runners to alert the British commander of the danger . This information enabled a British , Mohawk , and Seneca force to ambush the Patriots and their Oneida allies in the Battle of Oriskany . After this battle , in which Iroquois warriors fought on both sides , the war in the Mohawk Valley became particularly brutal . The Oneida and Americans retaliated against Brant by pillaging Canajoharie . Brant fled with her children to Onondaga , the Iroquois capital . Her departure was so precipitate that she had to leave most of her belongings behind . 
