Thomas Hill was born around 1837 in Rossie, New York, to George and Emily Hill. His father was a Scottish immigrant who earned a living as a farmer. By 1860, the family owned $3,600 of real estate and $800 of personal property. He grew up and attended school in Rossie.
He enlisted in the Union army on April 24, 1861, and he mustered in as a private in Company D of the 16th New York Infantry. The regiment took part in the Peninsula campaign and the Battle of Chancellorsville. He received a gunshot wound in the chest in the Battle of Salem Church on May 3, 1863. Confederates captured him soon afterward, and he died on May 17, 1863.