Archibald IRWIN was born in 1734 in Glencoe, Antrim, Ulster, Northern Ireland. He was an ensign in the French and Indian War in 1756. He was a major in the Continental Army. He died of Palsy on 23 Jan 1798 in Mercersburg, Franklin, Pennsylvania. He was buried after 23 Jan 1798 at Church Hill Cemetery, Pennsylvania. 

Ensign under Capt John Steel 1756 in the French and Indian War. Father also listed as James Irwin the Pioneer of Cumberland Co. of "Irwinton Mills" on the West Conococheague. Mentioned in brother James Irwin's will 1784. 

James Irwin, born in 1700, was a Scotch-Irish immigrant who came to Pennsylvania in 1729 with seven other Irwins. The Irwins operated mills, a bleaching plant and a smith shop in Northern Ireland. James Irwin in 1748 owned 540 acres in Peters Twp. just north of present day Mercersburg, Pennsylvania. By 1766 he owned a mill valued at three pounds 12 shillings and by 1769 the value of the mill was 10 pounds six shillings. 

During the Revolutionary War, Archibald Irwin's oldest son, James, began to do commissary duty for the Western Army at Irwinton's Mills. James Irwin organized pack horse trains to carry flour, meat and other provisions to Pittsburgh for the Western Army. James Irwin acted as an assistant commissary under the appointment of Col. George Morgan, who was Commissary General for the Western Army, whose headquarters were at Pittsburgh. 

Large quantities of flour were made at Irwinton's Mill, packed in kegs, each weighing about one hundred pounds, to be sent west. Flour was brought in from Washington County, Maryland. Large numbers of beef cattle were driven to Irwinton's plantation to be purchased, slaughtered and processed in a recently erected slaughter house, and sent to the Western Armies. James Irwin stated that the Pittsburgh Quarter Master Department had four brigades of pack horses each containing about one hundred horses, with one horse master and twelve riders to each brigade, to carry provisions west for the Army. The mill must have been busy and crowded, with one hundred pack horses being loaded, and with their drivers and horse master preparing for a trip over the mountains to Pittsburgh. 

Archibald Irwin died in 1798 and the plantation was given to his youngest son, Archibald Irwin II. Archibald Irwin’s oldest daughter, Jane, married William Henry Harrison, Jr., son of the General and President William Henry Harrison, at Irwinton Mills in 1824. Jane Irwin Harrison was mistress of the White House during the brief administration of the first President Harrison in 1841. Archibald Irwin IPs daughter, Elizabeth, married John Scott Harrison. In 1889 Benjamin Harrison, the oldest son of Elizabeth Irwin Harrison, became President of the United States. 

From the Book: "The Ancestry of Benjamin Harrison" 

Archibald Irwin, the great-great-grandfather of President Benjamin Harrison, appears to have been born in that country. Mrs. Newcomer of Indianapolis, among other information kindly furnished me, tells me that this Archibald settled where his son and grandson of the same name afterwards resided, four miles south of the site of Mercersburg, Franklin County, Pa. This was formerly in Peters Township, Cumberland County, and a list of owners of land in that Township in 1763 mentions an Archibald Irwin with two hundred acres, for which the warrants had already been issued, twenty acres being cleared, and nine sown, and with two horses and two cows. John, James, William, and another John appear in the same list, each having more acres cleared than Archibald. It is probable that this first Archibald, rather than his son,  the Ensign Archibald Irwin of the Rev. John Steel's company of Armstrong's battalion in 1756.