Major Alfred Mordecai, Jr. was born in North Carolina on January 3, 1804 and graduated from the United States Military Academy in 1823 with a commission in Ordnance.
He was Commanding Officer of Watervliet Arsenal, New York, from 1857 to 1861. In 1843, he conducted tests on gunpowder, with the idea of measuring muzzle velocity. This led him to construct a ballistic pendulum.
During the period 1838 to 1849, he served as Assistant to the Chief of Ordnance and as a member of the Ordnance Board. He went to Europe to study foreign systems of artillery. An elaborate report was issued and as a result of Major Moredecai's effort the great work entitled "Artillery for the United States Land Service" was published. This European study was an early Ordnance technical intelligence effort. Mordecai's work on the Ordnance Board was the predecessor of the work of the later Westervelt Board.
Being from the South, he would not fight against his own people in the Civil War, but at the same time honor and duty would not permit him to rebel against the flag of his country. He therefore resigned his commission on May 5, 1861. Major Mordecai died on October 23, 1887.