Seward was born in Auburn, New York. His father, William Henry Seward, Sr., had just taken office as Governor of New York when he was born, and his mother, Frances Adeline Seward, was the daughter of Judge Elijah Miller, a law partner of Seward who had built the family home in Auburn in 1816.
Educated at home, Seward became interested in finance and later started a partnership with Clinton McDougall, was private secretary to his father, then a U.S. Senator from New York, in 1860, and opened a private bank in Auburn in 1861. He left banking on August 22, 1862 to join the Union Army in the U.S. Civil War.
Seward was appointed lieutenant colonel of New York's 138th Infantry Regiment, which became the 9th New York Heavy Artillery Regiment in December 1862.[1][2][3] The regiment served in the defenses of Washington, D.C. until it was converted back to an infantry regiment and sent to the Army of the Potomac because of the losses sustained by that army in the Overland Campaign.[2] After fighting at the Battle of Cold Harbor,[2] Seward was appointed colonel of the regiment on June 10, 1864.[1][2]
A few weeks after Seward's promotion to colonel, his regiment was sent north to meet the threat to Washington, D.C. posed by Confederate Lieutenant General Jubal Early's Valley Campaigns of 1864.[1][2][3] Seward was slightly wounded in his arm and suffered a broken leg when his horse fell on him after the horse was shot at the Battle of Monocacy on July 9, 1864.[1][2][3] He was promoted to brigadier general on September 13, 1864 and in January 1865 was assigned to command a brigade in the Department of West Virginia, which he did until April 1865.[1][2][3] He was thereafter known within his family as "The General". Seward commanded the 3rd Division for 6 days after Confederate partisan rangers captured Brigadier General George Crook on February 20, 1865.[1][2][3]
Seward resigned his commission on June 1, 1865.[1][2] After the war, Seward returned to banking and lived with his wife, Janet MacNeil Watson Seward (1839–1913), in the family homestead in Auburn, New York. In addition to his banking career, he engaged in politics, charitable work, and patriotic and historic societies and he became a director of several corporations.[2] He had three children: Cornelia Margaret Seward Allen (1862–1921), William Henry Seward III (November 10, 1864–February 16, 1951)[4] and Frances Janet Seward Messenger (1880–1957).
William Henry Seward, Jr. died in Auburn, New York on April 26, 1920 at the age of 80, and is buried in Auburn's Fort Hill Cemetery,[1] next to his father.
