Major-General Arthur St. Clair was a Scottish-born American military officer and politician. Born in Thurso, Caithness, he served in the British Army during the French and Indian War before settling in the Province of Pennsylvania. During the American Revolutionary War, he rose to the rank of major general in the Continental Army, but lost his command after a controversial retreat from Fort Ticonderoga. By the mid-1770s, St. Clair considered himself more of an American than a British subject. In January 1776, he accepted a commission in the Continental Army as a colonel of the 3rd Pennsylvania Regiment. He first saw service in the final days of the failed Quebec invasion, where he saw action in the Battle of Trois-Rivières. In April 1777, St. Clair was given command of Fort Ticonderoga. His outnumbered garrison could not resist British General John Burgoyne's larger force in the Saratoga campaign; thus, St. Clair was forced to retreat at the resulting siege on July 5, 1777. He successfully evacuated his men, but choosing not to stand and fight permanently damaged his sterling reputation. In 1778, he was court-martialed for the loss of Ticonderoga.

The court exonerated him and approved his return to duty, but he would never hold a command again during the Revolution. He still saw action, however, as an aide-de-camp to Washington, who retained a high opinion of him. St. Clair was at Yorktown when Lord Cornwallis surrendered his army. During his military service, St. Clair was elected a member of the American Philosophical Society in 1780. Following his discharge from the Army, St. Clair was elected to the Pennsylvania Council of Censors in 1783 and served as a delegate to the Confederation Congress, serving from November 2, 1785, until November 28, 1787. Under the Northwest Ordinance of 1787, which created the Northwest Territory, St. Clair was appointed governor of what is now Ohio, Indiana, Illinois, Michigan, Wisconsin and part of Minnesota. In March 1791, St. Clair succeeded the disgraced Harmar as Senior Officer of the new United States Army and was restored to his previous rank of major general. Arthur St. Clair died in poverty in Greensburg, Pennsylvania, on August 31, 1818, at the age of 81.