Captain Henry Metcalfe was born on October 29, 1847 and graduated from the United States Military Academy in 1868 with a commission in Ordnance.
He was the Executive Ordnance Assistant at Springfield Armory where, in 1873, he invented the first detachable magazine for small arms.
As an instructor at West Point in Ordnance and Gunnery in 1886, he wrote a book on the subject which brought the whole course up to date. This task, with the wide research and mathematical calculations it necessitated, had a recognized effect in reforming the Military Academy's curriculum.
In 1876, as a first lieutenant, Captain Metcalfe prepared the Ordnance display for the International Exhibition at Philadelphia. He then prepared an extensive and detailed report of the War Department participation in the Exhibition. The report included details of United States and foreign ordnance displays and thus constituted a valuable reference on ordnance materiel.
Captain Metcalfe, who was promoted to that rank in March 1879, retired on October 26, 1893 due to an eye injury. He died on August 17, 1927 and was buried at the United States Military Academy.