DUNCAN, Johnson Nelly, soldier, born in York, Pennsylvania, 19 March 1827 ; died in Knoxville, Kentucky, 18 December 1862. He was graduated at the U. S. military academy in 1849, and became 2d lieutenant in the 3d artillery, serving in the Florida hostilities against the Seminole Indians. From 1850 till 1853 he was attached to Forts Sullivan and Preble in Maine, on garrison duty, and was then assistant on the Northern Pacific railroad exploration till December 1854. He resigned from the army in January 1855, and became superintendent of repairs in New Orleans, in charge of the branch mint, marine hospital, quarantine warehouse, and Pas a l'Outre boarding station. From 1859 till 1860 he was professionally occupied as civil engineer, surveyor, and architect in New Orleans, becoming also, in 1860, chief engineer of the board of public works of the state of Louisiana. At the beginning of the civil war he entered the Confederate army as colonel, but soon was appointed brigadier general from Louisiana. He commanded Forts Jackson and St. Philip at the time of their capture by Admiral Farragut, on 25 April 1862, and became a prisoner of war.