Enlisted as a Private in Company D, 35th Infantry Regiment Pennsylvania on 02 July 1863.
Mustered out Company D, 35th Infantry Regiment Pennsylvania on 07 August 1863.

Official Congressional Medal of Honor Citation:
Rank and organization: Corporal, Company D, 6th Pennsylvania Reserves. Place and date: At Gettysburg, Pa., 2 July 1863. Entered service at: ------. Birth: Bedford County, Pa. Date of issue: 3 August 1897. Citation: Was 1 of 6 volunteers who charged upon a log house near the Devil's Den, where a squad of the enemy's sharpshooters were sheltered, and compelled their surrender.



'Sixty-three Medals of Honor were awarded for heroism in the battle at Gettysburg, Pennsylvania, July 1 - 3, 1863.. Corporal Thaddeus Smith was cited for his own heroism in one of only two actions wherein more than one man earned the Medal of Honor for the same action. On the afternoon of July the 6th Pennsylvania Reserves were engaged with enemy forces north of Devil's Den in severe fighting that was taking a deadly toll on the Union forces. When it was determined that most of the fire was coming from a small log cabin on the flank of the regiment, Corporal Smith, along with Sergeants George Mears, John Hart, and Wallace Johnson, and Corporals Chester Furman and Levi Roush, volunteered to make a daring attack on the cabin to dislodge the enemy sharpshooters. The six men moved stealthily towards the cabin, but were soon discovered by the rebels and came under a heavy fire. Bravely they ignored the danger and rushing forward, knocked down the barricades in front of the door and overwhelmed the enemy. Capturing the enemy strong point, they quieted the fire on their comrades and returned to their regiment with more than a dozen prisoners. All six were awarded the Medal of Honor for this daring assault.'

Transferred May 31, 1864 to 191st PA

transferred to 191st PA May 31, 1864