In July 1861, upon the outbreak of the American Civil War, Reed enlisted as First Lieutenant in the 2nd Iowa Independent Battery Light Artillery.

In 1872, he was appointed by Governor Cyrus C. Carpenter as judge of the 13th district court from 1872 to 1884.

After winning the general election, Reed served in the Fifty-first Congress.

In June 1891, he was named by President Benjamin Harrison as the chief justice of the new United States Court of Private Land Claims, a court created to decide land claims guaranteed by the Treaty of Guadalupe Hidalgo, in the territories of New Mexico, Arizona, and Utah, and in the states of Nevada, Colorado, and Wyoming.

He then resumed the practice of law in Council Bluffs, where he died on April 2, 1925.