at the academy until 1827 as an assistant professor of mathematics and as a principal assistant professor of engineering. One of the students he taught during this period was Cadet Robert E. Lee. In the summer of 1828 Greene married Mary Elizabeth Vinton, sister of his best friend at West Point, David Vinton. Elizabeth gave birth to three children over the next four years: Mary Vinton, George Sears, and Francis Vinton Greene. While assigned to Fort Sullivan in Eastport, Maine, in 1833, tragedy struck Greene's family: Elizabeth and all three of their children died within seven months, probably from tuberculosis. To ease the pain on his mind and to escape the isolation and loneliness of peacetime Army garrison duty, he immersed himself in study of both the law and medicine, coming close to professional certification in both by the time he resigned his commission in 1836 to become a civil engineer. Greene built railroads in six states and designed municipal sewage and water systems for Washington, D.C., Detroit, and several other cities. In New York City, he designed the Croton Aqueduct reservoir in Central Park and the enlarged High Bridge over the Harlem River. He was one of twelve founders in New York City of the American Society of Civil Engineers and Architects. While on a trip to Maine for railroad surveying, he met Martha Barrett Dana, daughter of Samuel Dana, a prominent Massachusetts politician. They were married in Charlestown, Massachusetts, on February 21, 1837. They had six children together, including four sons (three of them later served in the military), one daughter, and one son who died in infancy. Civil War Despite being over 60 years old and having been out of the Army for 25 years, the crisis of the Union compelled Greene to seek to rejoin the service. He was essentially apolitical and was not an abolitionist, but he was a firm believer in restoring the Union. He was appointed colonel of the 60th New York Volunteer Infantry on January 18, 1862. The regiment of upstate New Yorkers had been dissatisfied with their colonel and the company commanders had petitioned for his removal. Governor Edwin D. Morgan, although initially reluctant to appoint Greene because of his age, saw his 13 years of regular army experience as a solution to his political/military problem. During this period, Governor John A. Andrew of Massachusetts was also prepared to offer Greene