Adamson Tannehill was born May 23, 1750, in Frederick County, Maryland,^[1][2] the oldest of nine children born to John Tannehill, owner of a tobacco plantation, and Rachel Adamson Tannehill.^[2] Adamson's maternal grandfather took a special interest in the grandchild who bore his name, and he provided "such pecuniary assistance as to secure a fine education" for him.^[3] Little else is known of Adamson's youth and upbringing. No portraits of him are known to exist; family records state that as an adult he "was six feet in height, well proportioned and of commanding appearance".^[4]

At the age of 25, Tannehill was among the first volunteers to enlist in one of the earliest American military units to form when the American Revolutionary War started in the spring of 1775.^[5] He served in the Continental Army, initially as a sergeant in Captain Thomas Price's Independent Rifle Company,^[5] one of the original ten independent rifle companies from Pennsylvania, Maryland, and Virginia authorized by the Continental Congress on June 14, 1775.^[6] He received his officer's commission dated January 1, 1776, as a third lieutenant,^[7] while serving at the siege of Boston.^[3] In mid-June the same year, Tannehill and his company were incorporated into the newly organized Maryland and Virginia Rifle Regiment, when he advanced to second lieutenant.^[8] In the summer and fall of 1776, many of the regiment's officers, including Tannehill, conducted recruitment and initial training of new enlistees in the two states and moved them to New York to join the regiment.^[9]

On November 16, 1776, a large portion of Tannehill's regiment was captured or killed at the Battle of Fort Washington on northern Manhattan Island.^[10] The remainder—about one-third of the unit including Tannehill—continued to serve actively in the Continental Army.^[11] That winter, they participated in the battles of Trenton and Princeton and the Forage War.^[12] The following spring, they were administratively attached to the 11th Virginia Regiment because of the losses suffered by their rifle regiment.^[13] The riflemen also provided an experienced, if small, force to bolster this newly formed Virginia unit.^[14] Tannehill was promoted to first lieutenant on May 18, 1777,^[15] and the following month he was attached to the newly organized Provisional Rifle Corps commanded by Colonel Daniel Morgan.^[16] Deployed as specialized light infantry, this regiment-size force of about 500 riflemen played a major role in the Battles of Saratoga and the Battle of White Marsh in late 1777 and a peripheral role in the Battle of Monmouth in June 1778. The rifle corps was also notable for its scouting and outpost duties in defense of the Continental Army's Valley Forge encampment during the winter and spring of 1777–1778.^[17]

Tannehill was detached from the rifle corps after the Battle of Monmouth in mid-1778 and returned to the Maryland and Virginia Rifle Regiment (his permanent unit).^[17] This occurred when Lieutenant Colonel Moses Rawlings, the regiment's commander, was marshaling the remnants of his unit and recruiting new members while stationed at Fort Frederick, Maryland.^[18] (Rawlings had been captured at the Battle of Fort Washington and recently exchanged from British captivity.)^[19] In furtherance of Rawlings' effort to muster the members of his regiment, General George Washington ordered in early 1779 that "all the men belonging to…Rawlings's Regimt. now doing duty in the line are to be delivered up to Lieutenant Tanneyhill [sic] of said regiment upon his demanding them."^[20] Tannehill supervised the assembly of the regiment because of the temporary absence of its two senior officers at that time.^[21]

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 of the war's western front from Indian raids.^[21][22][23] The high mark of this effort, in which Tannehill and his regiment took part,^[24] was the 605-man Brodhead Campaign against hostile Mingo and Munsee Indians conducted in the late summer of 1779.^[25][26] Continental Army Western Department commander Colonel Daniel Brodhead considered the Iroquoian Mingo to be "the principal distressers of [the] settlements" at that time in western Pennsylvania and eastern Ohio.^[27] Consequently, the rifle regiment was also deployed in detachments to support Continental infantry contingents at Fort McIntosh,^[28] Fort Laurens,^[29] Holliday’s Cove Fort,^[30] and Fort Henry^[31][32] in western Pennsylvania, eastern Ohio, and adjacent northern West Virginia. Tannehill was promoted to captain on July 29, 1779,^[33] and by late 1780 commanded the regiment and was commandant of Fort McIntosh.^[34][35]

Tannehill was discharged from service on January 1, 1781,^[36] when several regiments, including Tannehill's, were disbanded as a result of Congress's major 1781 reorganization of the Continental Army instituted to reduce expenditures and increase organizational efficiency.^[37] In a letter to Major General William Smallwood penned on Christmas day of 1780, Tannehill made note of his regiment's formal disbanding and the termination of his own period of service that were to occur seven days later. (Smallwood was Maryland's highest ranking military officer at this time in the war.) Tannehill's objective was to gain Smallwood's personal assistance in securing a position for himself in the Maryland Line because of his "great desire of Continuing in the Service of [his] Country".^[38] Tannehill further affirmed that "I shall do every thing [sic] in my power to keep [the men] together till I have some instructions [from you] respecting them".^[38] Smallwood could not grant Tannehill's request because of the recent congressional directive. The Maryland and Virginia Rifle Regiment was the longest-serving Continental rifle unit of the war.^[39]

Tannehill was admitted as an original member of the Society of the Cincinnati in the state of Maryland when it was established in 1783.^[40][41]

After his Revolutionary War service, Tannehill settled in frontier Pittsburgh, as did many other Revolutionary War officers.^[42] He initially engaged in farming and was a tavern owner^[43][44] and vintner.^[45] He was also a landowner and a "large buyer"^[46] of land lots in early Pittsburgh—land purchased directly from the heirs of William Penn.^[47] From 1784 until around 1792, Tannehill owned and operated the riverfront Green Tree Tavern and Inn located midblock between Market and Wood Streets in Pittsburgh.^[47][48] He resided in the adjacent house until 1787 when he moved to his new Grove Hill estate, which became popular as a local center for political meetings while owned by Tannehill.^[49] The property was located on Grant's Hill just northeast of Pittsburgh in what is now the city's Hill District. One of the buildings at Grove Hill, known as "the Bowery", was the site of large annual social gatherings hosted by Tannehill where citizens of Pittsburgh came together each Fourth of July "to hail with joyful hearts the day that gave birth to the liberties and happiness of their country".^[49][50] Tannehill lived at Grove Hill until his death in 1820.^[51]

Tannehill began public service no later than 1794 when the borough of Pittsburgh was established.^[52] That year, he was appointed president of the Pittsburgh Fire Company^[53] and elected one of three surveyors of Pittsburgh.^[54] In March 1790, Tannehill had unsuccessfully solicited a public appointment in the administration of President George Washington by writing to Washington's personal secretary, Tobias Lear, who had visited Pittsburgh and lodged with Tannehill at his inn four years before.^[55] In his note, Tannehill mentioned that Washington "has some acquantance [sic] of me, which may probably have some weight", referring to instances of direct interaction the two men had during the American Revolution.^[3]

Sometime before 1794, Tannehill was appointed a justice of the peace of Allegheny County,^[53] an administrative unit that included Pittsburgh. In October 1800, he was temporarily removed from this office 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.^[56] He was issued a reprimand and fined fifty dollars.^[57] Tannehill was quickly reinstated to office in January 1801 by Governor Thomas McKean, the former chief justice of Pennsylvania, was refunded his fine,^[57] and subsequently held several prominent elected and appointed public offices. Tannehill believed the charges against him had marred his reputation and vehemently disclaimed any guilt for the rest of his life. His resentment toward whom he called "two of the most unprincipled scoundrels who ever appeared before a Court of Justice" and what he characterized as their "false swearing and vile slander" was still strong 15 years later when he reflected on the affair in his will.^[58]

Tannehill was active in the state militia, serving as a lieutenant colonel in the Westmoreland County militia starting in 1788.^[47] On August 3, 1811, Pennsylvania Governor Simon Snyder promoted Tannehill to major general of a Pennsylvania militia division drawn from Allegheny, Armstrong, and Indiana counties.^[47]

Starting in 1804, Tannehill served as a founding member of the board of directors of the Pittsburgh branch of the Bank of Pennsylvania^[59] after leading Pittsburgh citizens in a petition to establish the branch.^[50] (This was the first bank established in Pittsburgh and the first one west of the Allegheny Mountains.)^[59] He was then appointed by the Pennsylvania state legislature as one of five turnpike commissioners for the state starting in 1811.^[60] The commissioners' task was "to view the different routes for…turnpike roads from Harrisburg to Pittsburgh".^[60] Tannehill was also chosen by the state legislature as an elector of the 1812 federal Electoral College for the state of Pennsylvania.^[61]

After the War of 1812 broke out, Tannehill served as a brigadier general commanding four infantry and rifle regiments of United States Volunteers.^[62] In his most significant effort of the war, Tannehill and his brigade marched to the American encampment at Buffalo, western New York, in October and November 1812.^[63] There, they were to join combined American forces (regular, militia, and volunteer) preparing to establish a foothold on the Canadian side of the Niagara River before the onset of winter. However, they did not arrive in time for the failed invasion, marked by the British victory at the Battle of Queenston Heights in present-day southern Ontario. Tannehill's military duties during the limited duration of the war in western Pennsylvania lasted from September 25 to December 31, 1812.^[1]

Meanwhile, outside of public office, Tannehill served as an inaugural trustee of the First Presbyterian Church of Pittsburgh starting in 1787.^[64][65] He was also a member of the fraternal Tammany Society, which was founded after the American Revolution in several American cities, including Pittsburgh.^[66] The society focused on the celebration of American identity and culture. Members of the society in its earliest years closely allied themselves with the Democratic-Republican party of Thomas Jefferson. Consequently, when Jefferson announced his intent to withdraw from public service in 1808, Tannehill, in his capacity as Grand Sachem (high official) of the Pittsburgh Tammany Society, wrote to "Brother" Jefferson, expressing "heartfelt regret" over his "resolution to retire from the duties of protecting thy children [of this tribe]".^[67][68]

Although Pittsburgh was a stronghold of the Federalist Party in the city's earliest years, between 1798 and 1800 the rival Democratic-Republican Party began to prosper under such men as Adamson Tannehill, who had become chairman of the city's Republican party by 1800.^[69] Tannehill was also a three-time candidate for the U.S. House of Representatives, initially representing Pennsylvania’s 11th congressional district in the election to the 12th United States Congress on October 9, 1810. He was defeated by fellow Democratic-Republican Abner Lacock, who garnered 51.0 percent of the vote; Tannehill earned 43.2 percent, and Democratic-Republican Samuel Smith received a distant 5.7 percent.^[70]

The high point of Tannehill's active political career was his election as a Democratic-Republican to the 13th United States Congress on October 13, 1812.^[1] Tannehill was elected to serve Pennsylvania's newly established 14th congressional district with 48 percent of the vote, defeating Federalist John Woods and Democratic-Republican John Wilson, who received 39.3 and 12.7 percent of the vote, respectively.^[71] Tannehill served from March 4, 1813, to March 3, 1815,^[1] casting 322 votes and missing 30.^[72]

Tannehill ran for reelection on October 11, 1814, again as a Democratic-Republican, in the 14th United States Congress. He narrowly lost his reelection bid, receiving 49.5 percent of the vote; his opponent, John Woods, whom he had defeated two years earlier, won with 50.5 percent of the vote.^[73]

Following his tenure in Congress, Tannehill served as president of the Pittsburgh branch of the Bank of the United States starting in 1817^[74] and ending with his death in 1820.

Tannehill died after a short illness at his Grove Hill home just outside Pittsburgh on December 23, 1820, aged 70 years and 7 months.^[1][75] He was survived by his wife, Agnes M. Tannehill,^{[76][77][78][79]} and his ward, Sydney Tannehill Mountain.^[80] Adamson and Agnes had no children.^[81] Tannehill was interred at his Grove Hill home,^[82] as specified in his will.^[83] His 1820 obituary relates that "his remains were accompanied to the grave by a large concourse of his fellow citizens and were interred with military funeral honors by two…Volunteer Corps" of the Pittsburgh area.^[75]

Tannehill's body was reinterred in Allegheny Cemetery in Pittsburgh on April 26, 1849,^[84] because urban spread and city road construction necessitated moving his Grove Hill grave. The archive files of a prominent Pittsburgh newspaper provide detail on this reinternment: "after the big fire in 1845, when [the Pittsburgh city] council extended the city limits to take in the farms on what is now the Hill district…it was found that in extending Wylie avenue, Colonel Adamson Tannehill's grave would be between the curbs…About 1851 [sic] [the] council decided to remove the colonel's remains to Allegheny cemetery. The Tannehill family objected, but [then] agreed to make the transfer themselves".^[85]

• The Political Graveyard
• The Society of the Cincinnati
• The American Revolution Institute