[4] A second church was built in the Federal style at the corner of Jonathan (now Summit) and Antietam Streets in 1823, and consecrated by the second bishop of Maryland.

During the American Civil War (1861-1865), Saint John's Church was attended by a large number of Southern sympathizers.

Henry Edwards, was decidedly pro-Union and served as the U.S. Hospital Chaplain at Hagerstown from Nov. 13, 1862 through March 5, 1863, in the aftermath of the battle of Antietam.

On the Sunday before that battle, he preached from Saint John's pulpit before a congregation of Confederate officers and soldiers, yet lifted up a prayer for Abraham Lincoln, the President of the United States.

Edwards did the same before “the whole of Longstreet’s division.”[5] The present church building, built in 1872, was an American adaptation of the Oxford Movement in sanctuary design.

Other features included coursed rows of rough-hewn blue limestone with stringcourses, sills and lintels of brownstone, stained-glass Gothic windows; and a bell tower with a stone steeple.

Two heavy oak doors, painted red, are covered with elaborate scrolled pattern in bronze reminiscent of the Lichfield Cathedral in England.

[6] In December 1871, a fire in the town's business district destroyed the Federalist style sanctuary built in 1832 at the corner of Jonathan and Antietam Streets.

In 1899, Mollie Magill Rosenberg, a former communicant, donated a high Gothic Altar and associated supporting pieces,[7] including a reredos.

The transformation later continued, most notably through the replacement of the original windows with stained-glass designs depicting the life of Christ, chronologically, more or less.

Above, a crossbridge (see the miniature passageway and small windows running laterally below the gables) connects what would have been the cathedral's north and south transepts.

The High Altar's base features a triptych of two Old Testament events laying foundations for Christ's priesthood.

The Last Supper, John 13-21 (center), was carved from a print of the mural by Leonardo da Vinci for dining room wall of the monastery Santa Maria delle Grazie (Milan, Italy).