The Reverend Anthony Toomer Porter, an Episcopal priest, formed The Holy Communion Church Institute to educate children orphaned during the Civil War. The school opened on December 9, 1867 with 425 boys and 125 girls. It was housed in the church Sunday School, located on the corner of Ashley Avenue and Cannon Street. After several years, girls were no longer accepted.
The school took possession of the U.S. Arsenal property on Ashley Avenue.
The name of the school was changed to the "Porter Academy", which is still its official name.
The unofficial name of the school became the "Porter Military Academy," though the students may have worn military uniforms before this.
The Porter Military Academy merged with the Gaud School and the Watt School.
The combined school was located on the Porter campus for one year while the present school was being built. The name of the school was changed to "Porter-Gaud School" and the military program was ended.
Porter-Gaud School moved to its present campus and included a Boarding Department until May 1974.