Man enlisted as a volunteer in the 98th New York Infantry Regiment unit of the Union Army in 1861 during the American Civil War and became a major. He participated in the battles of Yorktown, Williamsburg, and Fair Oaks. His health deteriorated due to exposure to the elements during the war and he was forced to resign from the military. He then returned to his home in Franklin County, where he continued as the district attorney. In 1863, Man went to Washington as chief of the Division of Organization in the office of the Controller of the Currency, afterward serving under Hugh McCulloch of the United States Treasury Department. In 1866 he became treasurer and general manager of the National Bank Note Company of New York City. Resuming the practice of law in 1871, he became general manager and agent of the Lorillard estates of New York City and stayed in that position until 1883.