[4]: 241–43 Moravian missionaries first established a mission at Friedenshütten ("Tents of Peace"),[5]: 92–93  near Bethlehem, Pennsylvania in 1744, but in 1745 decided to move some distance northwest of Bethlehem, to a site they named Gnadenhütten ("Tents of Grace," often written Gnadenhuetten and sometimes referred to as "Gnadenhütten on the Mahoney" to distinguish it from Gnadenhutten in Ohio), near the junction of Mahoning Creek and Lehigh River.

[11] In October and early November 1755, the communities of Penn's Creek and Great Cove were attacked and destroyed by Lenape and Shawnee warriors.

A boy escaped by jumping from a window, and another man had left the house immediately prior to the attack, having gone to lock the chapel door, and was unharmed.

[15] Susanna Nitschman, Martin's wife, escaped from the burning building, and was captured and held prisoner in Tioga County, Pennsylvania for six months until her death.

[4]: 242 [8]: 368 Colonel John Anderson arrived from New Jersey that night with a company of militia, but after being informed that over 500 Indians had swarmed the settlement,[17] he waited until the following day to approach Gnadenhütten.

[5]: 135 Governor Robert Hunter Morris ordered a company of 72 soldiers from Northampton County, under the command of Captain Hays, to guard the abandoned property at Gnadenhütten until it was safe for the residents to return.

This led to generalized panic among settlers in the area, and Benjamin Franklin was commissioned in Philadelphia to investigate the situation and devise a plan for the defense of Pennsylvania against further attacks.

[4]: 244 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.

[15] In his biography, he wrote that the Moravians had made preparations to defend Bethlehem and Gnadenhütten against further attacks: Franklin and his men then built Fort Allen in less than a week.

Situated on the northern slope of the Blue Mountain ridge near the Lehigh River,[14]: 222  it was essentially a stockade surrounding a well, a barracks, a storeroom, and a gunpowder magazine.