Codman was admitted to the bar in 1852 and practiced for a short time before entering the business world.

The Victorian Stick mansion was built by Charles L. Baxter based on John Hubbard Sturgis's plans for Andrew Lovell's Red House.

Following President Abraham Lincoln's July 1, 1862, call for three hundred thousand soldiers, the Cadets began recruiting a nine month regiment.

Codman led the regiment during the Battles of Kinston and White Hall, as well as in skirmishes in and around New Bern, North Carolina.

In 1884, Codman joined the Mugwump movement in support of Democrat presidential candidate Grover Cleveland due to his opposition to the Republican nominee James G. Blaine.