[1] A native of Sutton, Massachusetts, Sprague was a Captain of the 13th Connecticut Infantry Regiment in 1861 when the American Civil War began, and quickly rose to the rank of Colonel before being captured as a prisoner of war by the Confederate Army in 1864.

In 1865 he was released in a prisoner exchange, and remained active within the military until the end of the war.

[4] An early progressive voice in education, he served as president of Adelphi Academy in New York as it first opened its doors to female students.

He was valedictorian of his class, and in 1848 he entered Yale University to study law and literature.

[3][7] After leaving university, Sprague spent his time as a lecturer and tutor, while continuing his studies to earn his M.A..