Thaddeus Little was an 18-year-old farmer in Bristol when he enlisted in the 1st Maine in October 1861.
He was mustered in to Company K as a private and was promoted to sergeant on July 1, 1863, and to orderly sergeant on September 1, 1863.
He reenlisted on December 29, 1863, and was commissioned 2nd lieutenant November 28, 1864.
On March 25, 1865, he was promoted to 1st lieutenant and regimental adjutant.
During the charge on Confederate wagons near Sailor's Creek on April 6, 1865, he was badly wounded in the upper right arm. As Colonel Cilley later recalled, "Adjt. Little was fearfully, swearing mad, with a pistol shot in his shoulder, causing his sword arm to hang powerless at his side."
Little rejoined the regiment on June 4, 1865, and was mustered out with it on August 1, 1865.