Adamson Tannehill, a native of Maryland, is representative of the United States’ founding generation whose members were active participants in the early military and political events of their country's establishment. He was among the first volunteers to join the newly established Continental Army during the American Revolutionary War. He served for five and a half years, ultimately achieving the rank of captain and commander of the army's longest serving rifle unit. After the war, Tannehill and members of his family settled in Pittsburgh, his last military post of the conflict. He was an early leading citizen of Pittsburgh and a distinguished Pennsylvania politician who held several local and state appointed and elected offices, including one term as a U.S. Congressman; served on the founding boards of civic, state, and national organizations; and had prominent military roles in the state's post-Revolutionary War years.
Early years
Adamson Tannehill was born in Frederick County, Maryland, probably close to Frederick Town. He was the oldest of nine children born to John Tannehill, owner of a tobacco plantation, and Rachel Adamson. His maternal grandfather took a special interest in the grandchild who bore his name, and he provided funding to secure a fine education for Adamson. Little else is known of Adamson's earliest years. No known portraits of Tannehill exist; however, family records indicate that as an adult he “was six feet in height, well proportioned and of commanding appearance.” At the age of 25, he enlisted in one of the first American military units to form when the war with Great Britain started in the spring of 1775.
Revolutionary War service
Tannehill served in the Continental Army during the American Revolutionary War, initially as the first sergeant in Capt. Thomas Price's Independent Rifle Company, one of the original ten independent companies of riflemen from the frontier regions of Pennsylvania, Maryland, and Virginia authorized by the Continental Congress on June 14, 1775. He received his commission dated January 1, 1776, as a third lieutenant while serving at the Siege of Boston. In June 1776 Tannehill and his company were incorporated into the newly organized Maryland and Virginia Rifle Regiment, at which time he advanced to second lieutenant. Later that year a large portion of his regiment was captured or killed at the Battle of Fort Washington on northern Manhattan Island. However, those members of the unit not taken in the battle, including Tannehill, continued to serve actively with Washington's Main Army, participating in the Battles of Trenton and Princeton, and in the spring of 1777 were administratively attached to the 11th Virginia Regiment. Tannehill was promoted to first lieutenant on May 18, 1777, and the following month he was attached to the newly organized Provisional Rifle Corps commanded by Col. Daniel Morgan, which played a major role in the Battles of Saratoga and a peripheral role in the Battle of Monmouth. He returned to the Maryland and Virginia Rifle Regiment in mid-1778 when Lt. Col. Moses Rawlings, the regiment's commander who had been exchanged from British captivity earlier that year, was marshaling the remnants of his unit and recruiting new members while stationed at Fort Frederick, Maryland. In early 1779 Tannehill and the regiment were assigned to Fort Pitt of present-day western Pennsylvania where they supplemented other Continental forces engaged in the defense of frontier settlements from Indian raids. Tannehill advanced to the rank of captain on July 29, 1779, and he commanded the regiment in late 1780. He was discharged from service on January 1, 1781, when his unit was disbanded.
Early Pittsburgh
After the war Tannehill settled in Pittsburgh, as did a number of other Revolutionary War officers, including his brother Lt. Josiah Tannehill. He initially engaged in agricultural pursuits and was a tavern owner and vintner, president of the Pittsburgh Fire Co., and a trustee of the first Presbyterian church in Pittsburgh. He later served as a local Justice of the Peace; lieutenant colonel of Westmoreland Co. militia starting in 1788; an original member of the Board of Directors of the Pittsburgh branch of the Bank of Pennsylvania, the first bank in Pittsburgh, starting in 1804; one of five turnpike commissioners for the state starting in 1811; major general of Pennsylvania Volunteers during the War of 1812; and president of the Pittsburgh branch of the Bank of the United States starting in 1817. The high point of Tannehill's active political career was his election as a Republican to the Thirteenth U.S. Congress for the period 1813–1815. He was an unsuccessful candidate for reelection in 1814 to the Fourteenth Congress. In October 1800, Tannehill was temporarily removed from his office of Justice of the Peace after being convicted of extortion related to an event that occurred five years before in which he was alleged to have charged two shillings more than was allowed by law for two probates. Although he was quickly reinstated to office in January 1801 by Governor Thomas McKean, the former Chief Justice of Pennsylvania, and subsequently held several prominent public offices, Tannehill believed the charges against him, likely born out of the contentious political conditions of the time, had marred his reputation. He vehemently disclaimed any guilt for the rest of his life.
Death
Tannehill died near Pittsburgh in 1820 at the age of 70. He was survived by his wife, Agness Morgan Tannehill, and his ward, Sydney Tannehill Mountain. Tannehill was interred in the churchyard of the First Presbyterian Church and reinterred in Allegheny Cemetery in Pittsburgh in 1849.
