MERCER, HUGH, 1721-77; b. in Aberdeen, Scotland; educated at the university there; entered the medical profession, and served as assistant-surgeon in the army of prince Charles Edward, the "young pretender," in 1743. The insurrection proving a failure, he emigrated to A merica in 1747, settling.as a physician near the present town -of Mercersburg, Penn. 1 e served as a volunteer in Braddock's canapaign, was appointed capt., and so severely wounded in the battle on the Monongahela that lie was unable to keep up with the other fogitives from that disastrous field, wandered for several weeks alone in the forest, until last he reached fort Cumberland, 100 m. from the point of departure. For his courage in this epedition he received a medal from the city of Philadelphia. In 1758 he was promoted to the rank of lieut.col., accompanied gen. Forbes to fort Duquesne, now Pittsburg, and commanded the post for some time. After
this he settled as a 'plivsician inFrederick.sburg, Va., but entered zealously into the revo lutionary conflict. Ire organized and drilled the miuute-men of Virginia in 1775, and the militia in 1776, and at Washington's request was chosen a brig.gen. by congre,ss-, June 5,1776. He commanded a column in the attack on Trenton, and led the advance in the night march on Princeton, which lie had himself advised. Early in the battle there he was mortally wounded and left for dead on the field. Being discovered alive, he was taken to a neighboring farm-house, where he. expired in the arms of maj. Lewis, his aid-de-camp. His funeral in Philadelphia is said to have been attended by 30,00ff people, and a monument to his memory was erected at Laurel Hill cemetery in 1840. His son, Huon, was educated at the expense of the nation.