The son of a wealthy farmer from McGrawville, New York, Daniel Scott Lamont was educated at New York Central Academy and Union College, leaving college early to pursue a journalism career. Lamont entered politics when New York Democratic leader Samuel Tilden hired him as a clerk in the state party office.

Through his party connections, Lamont was hired by Governor Grover Cleveland as his military secretary in 1882. When Cleveland was elected President two years later, Lamont moved to Washington and served as his personal secretary, running the daily operations of the White House during Cleveland’s first term.

After Cleveland regained the presidency in 1888, Lamont became secretary of war, advising Cleveland in several crises, including the 1894 Pullman strike and the 1895 border dispute between Great Britain and Venezuela. Lamont instituted some modernizing reforms in the Army and announced the virtual end of warfare between federal forces and Native Americans, recommending that remaining Apache prisoners at Fort Sill be freed.

With the end of the Cleveland administration in 1897, Lamont entered private life as the vice president of the Northern Pacific Railroad. He died from a heart attack on July 23, 1905, in Millbrook, New York.