The Iroquois League had recently taken on the Seneca nation as probationary members. This meant the Seneca lost their political autonomy, worse the League was now divided with a minority of tribes inclined to Onontio. Indian politics was as complex as politics anywhere but fear of the densely populated and land hungry British colonies now dominated decision taking.
A group of Virginia land speculators, including the soon to be famous George Washington, were in a cabal with Mohawks to establish a claim Seneca territory and then sell it to settlers at a huge profit.
While this was unfolding Washington and The Half King, a prominent Mohawk, were involved in the killing of a French emissary. The Seneca whose territory this occurred in were appalled. Ontontio would surely wreak vengeance.
Washington, despite fearing his career was over, found his luck held. The royal and colonial authorities decided that attack was the best form of defence. The part time colonial militia was ordered to concentrate, Ranger companies were gathered and British regulars and artillery committed to the offensive.
Some effort was made by the British to adapt to wilderness warfare by lightening the load carried by regular troops and adapting their clothing. The Anglo-American forces had a huge advantage in numbers, and were not lacking in skill or morale, but in terms of wilderness fighting they were at the beginning of a very steep learning curve.