Unity Church was the first Presbyterian church established west of the Allegheny Mountains. It began before the American Revolution and before Westmoreland County or even Pennsylvania had clear boundaries. Soon after the French and Indian War, settlers in this rugged area, mainly Scotch-Irish Presbyterians, moved westward along the route laid out by the English Army under General Forbes and gathered for worship at Proctor's Tent, a crude shelter on John Proctor's farm southwest of this site. Beginning in the 1760s, Presbyterian missionaries conducted services there, and pioneer families traveled as far as eight miles on horseback, bringing rifles for defense from Indians. In 1780, six years after a land grant established a burial ground and meeting place for the Unity congregation, the settlers built an unheated log church on a high point of the property. After fire destroyed that first building in 1829, the growing congregation erected a much larger brick church on the same hilltop. Unity's numbers later declined as Latrobe was incorporated in 1854 and Unity opened a mission there in 1857; in 1869 that mission became the Latrobe Presbyterian Church and drew more than one hundred members from Unity. By 1874, the second church was torn down and replaced with the smaller brick church that still stands. On October 11, 1920, the remaining members voted to dissolve the congregation and transfer the cemetery and church building to the Unity Cemetery Association, composed mostly of former members. Though the building stood neglected for years, donations beginning in the 1930s and continuing through the 1950s from the Mellon and Scaife families, the Rogers and McFeely families, and the Saxman family restored the third church, now called Unity Chapel. Beginning on April 1, 1954, worship services resumed, and later support from the Mellon, Rogers, and Palmer families, together with memorial donations to the Unity Chapel Endowment Fund administered by the Latrobe Presbyterian Church, maintained and improved it as a place of worship and celebration.