[6] In late 1755, Colonel John Armstrong wrote to Governor Robert Hunter Morris: "I am of the opinion that no other means of defense than a chain of blockhouses along or near the south side of the Kittatinny Mountains from the Susquehanna to the temporary line, can secure the lives and property of the inhabitants of this country, the new settlements being all fled except Shearman's Valley.

[8]: 685 On February 9, 1756, Governor Morris wrote to General William Shirley: For the defense of our western frontier I have caused four forts to be built beyond the Kittochtinny Hills.

[7] The fort was located near a Native American village known as Sugar Cabins,[12] at the eastern end of the Forbes Road and close to a well-traveled Native American trail leading from central Pennsylvania to the Ohio Country, with the intent that the fort would serve to monitor the passing of Indians engaged in trading as well as any war parties.

[1] Soon after this, Elisha Salter, Commissary General, visited Carlisle and found the civilian populace abandoning their settlements in terror, after a series of brutal raids by Lenape and Shawnee warriors.

[15]: 392 In September, Armstrong led the Kittanning Expedition, rescuing 11 captives and killing the feared warrior Captain Jacobs.

[16]: 164–65 By 1757, Fort Lyttleton began to attract Cherokee Indians seeking to support British troops as auxiliaries and also spies.

In June 1757, Armstrong received reports that "a large Reinforcement of French and Indians from Canada & Mississippi" at Fort Duquesne "wou'd...endeavor to cutt off the back Inhabitants."

This order was evidently not obeyed, and on June 28, Stanwix wrote to Armstrong that he had "augmented the Garrison at Fort Lyttleton, 150 Men.

[15]: 477 In June 1763, George Croghan raised a volunteer company of 25 men to re-occupy the fort in response to Pontiac's War.