During the period of the American Revolution, the Reverend Amos Thompson settled in Loudoun County near Leesburg and in 1775 accepted calls to two united congregations namely, Catoctin and Gum Springs.  He was from the college of New Jersey, and a student of John Witherspoon.  He was absent during the Revolutionary years while he served as chaplain in the Continental Army.  Rev. David Bard, also a Princeton graduate, was sent as missionary to this area.  His annual salary while at Catoctin was 150 bushels of rye, 50 bushels of wheat, and 200 bushels of Indian corn.

After the Revolution, the Catoctin Church fell apart and the Rev. David Bard was dismissed from the charge.  He was ordered by the committee that released him to supply Leesburg until the next meeting of Presbytery.  There is no record of a church building at that time.  If there was an organization at that time, it may have worshipped in a private home, in the free church building at Gum Springs, Catoctin ("The Grove") or in the Courthouse.  At that time, Leesburg had a Courthouse, the old stone Methodist Church, a considerable number of log houses, and a few of stone and brick.  There were an extraordinary number of taverns and ordinaries.

The years following the Revolution saw a great poverty among the people in this area so it was a tribute to their faith and consecration that by 1802 the members of the Presbyterian Society could plan to build a Church.  The Society bought at public auction on November 9, 1802 most of the lot where the present church building now stands - one half acre for $80.  This lot was outside the area of Leesburg laid off by Nicholas Minor.  The deed to the property is on record at the County Clerk's office and specified that "it is for the sole use and purpose of a burial ground and place of worship to be conducted agreeable to the manner prescribed by the General Assembly of the Presbyterian Church of these United States forever."  After the purchase the members of the Society were appointed to enter into agreement with W. Wright to build a church "of brick 40 feet by 30 feet in the clear".  There is a tradition that the members themselves did the actual work of erecting the building as there was brick year nearby and there are still some hand hewn benches in the building, this may be true.

The church was dedicated on Sunday, May 4th, 1804 by the Rev. James Hall and 27 member were received into membership.  Dr. Hall was the Moderator of the General Assembly and he was on his way to the meeting in Philadelphia from his home in Bethany, NC where he was to preach the opening sermon on May 17, 1804.  James Hall was one of the great pioneers working to establish the Presbyterian Church in the South, having already been as far as Natchez organizing missions.  During the Revolution, Hall organized a troop of cavalry and served as chaplain.

We can imagine the great joy that came to the Leesburg Presbyterians with this service; their goal to build and organize a church had been fulfilled.  But sorrow was experienced soon when the Rev. Amos Thompson died on Sep. 8, 1804.  He was the first person buried in the new church yard.  His grave is near the west wall of the church.  Thompson's death was a severe loss to the church and the community where he was counselor, neighbor, pastor , and friend to the people.  We may judge the affection given him and the eminence he had attained by the fact that Dr. Moses Hoge came to Leesburg to conduct Mr. Thompson's funeral.  Dr. Hoge was an outstanding Presbyterian minister of his generation and shortly after this became President of Hampden-Sydney College.  Rev. Thompson's will revealed expressions of his selfless life.  He was a  man of means and a large land owner.  After a period of three years, he ordered his slaves set free, also a tract of land was sold and the proceeds bequeathed to the College of New Jersey to be used to educate apparently pious young men to the Gospel ministry.