Theodore K. Scheffer was born around 1839 in Pennsylvania to Theodore and Louisa Scheffer. His father was a printer who owned $5,000 of real estate and $1,000 of personal property in 1860. He grew up and attended school in Harrisburg, Pennsylvania, and by 1860, he was also working as a printer. He enlisted in the Union army on February 21, 1862, and mustered in as a captain in Company A of the 107th Pennsylvania Infantry on May 22.
The regiment took part in the Second Battle of Bull Run, the Battles of Antietam, Fredericksburg, Chancellorsville, and Gettysburg, the Overland Campaign, and the siege of Petersburg. He mustered out sometime after August 1864. He returned to Harrisburg after leaving the army, and he married Barbara Royer on March 7, 1867. They had at least four children: Warren, born around 1867; Paul, born around 1873; Royer, born around 1876; and Ross, born around 1876. He worked as a flour merchant after the war, and by 1870, he owned $300 of personal property. By 1880, he was working as a clerk in the post office. He died in Harrisburg in 1906.