During the Civil War he enlisted in the 3rd Missouri Infantry, where he rapidly rose through the ranks due to his engineering ability. After the War, he lived in St. Louis and was very involved in the construction of the Eads Bridge. As a result of his superior engineering ability during this project, he was elected by the citizens of St. Louis as the first president of the Board of Public Improvements in 1877. He served until 1890, when he resigned to accept a presidential appointment to be a member of the Mississippi River Commission. While president of the board, many of his ideas and projects were copied by other large cities. [http://home.usmo.com/~momollus/CiCmtg/Flad.htm]