He was reared and educated in Dauphin County with siblings: Jacob Franklin (1841–1916), Edwin (born circa 1845), Henrietta C. (1849–1932), and Adeline H. (1853–1943).

[3] In 1850, Thomas Hoffman resided with his parents and siblings, John, Edwin, and Henrietta, on the family's farm in Lykins Township.

After enrolling at Philadelphia on August 10, 1861, he then officially mustered in that same day as a private with Company E of the 72nd Pennsylvania Infantry (also known as the "Fire Zouaves").

[13] During the opening days of this latter campaign, Hoffman was detailed, on April 1, as acting engineer officer with the 3rd Division, 9th U.S. Army Corps.

[14] Interviewed later in life, Hoffman described what happened that day:[15] During the week that we were stationed at Steadman our division was ordered to capture Lee's works.

The rebels made a great effort to retake the forts, making numerous charges, but we succeeded in holding them back during the entire day.

When the line officers discovered that there was some one to take charge of the regiment they immediately rallied the men and kept them in position.Recognized for his valor that day, Hoffman was promoted by brevet to the rank of major on March 25.

Less than a month later, on June 27, 1865, he wed Sallie F. Shindel (1843–1890) at Saint John's Lutheran Church near Berrysburg in Lykens Township, Dauphin County.

That year, he became a widower when his wife, Sallie, passed away in Mount Carmel on April 2, and was laid to rest at the Pomfret Manor Cemetery in Sunbury, Pennsylvania.

[24] By the turn of the century, Hoffman was working as a bookkeeper for the Meadow Brook Coal Company, and residing with his second wife at the boarding house operated by Margaret Kries and Marion Cantner at 124 Adams Avenue in Scranton, Pennsylvania.