Casper Thenner was born in 1831 in Germany or the Netherlands.
Casper immigrated to America and settled in western Michigan sometime before the war broke out.
He stood 5’4” with blue eyes, light hair and a light complexion and was a 30-year-old laborer possibly living in Shiawassee or Kent County when he enlisted in Company C on May 13, 1861. (Company C was made up largely of German and Dutch immigrants, many of whom lived on the west side of the Grand River in Grand Rapids. This company was the descendant of the old Grand Rapids Rifles, also known as the “German Rifles,” a prewar local militia company composed solely of German troopers.) He was taken prisoner on July 1 or 2, 1862, at White Oak Swamp, Virginia, confined at Richmond, Virginia, and possibly paroled in mid-September.
According to the Richmond Dispatch of September 15, 1862,
Three thousand three hundred of the Yankee prisoners left Richmond on Saturday for Varina to be exchanged. – Such as could not walk were conveyed away in wagons. The officers, of which there were 61, went in carriages, provided for the purpose. As the long line filed past the C. S. Prison, on Cary Street, they greeted their less lucky compeers with a feeble cheer. A small cavalry escort accompanied them down. Another large gang were started for Aiken’s landing, on James river, yesterday morning. During Saturday and Sunday five thousand two hundred and twenty-eight were sent away. This leaves on hand only about seven hundred, a good many of whom are in the hospital under treatment for wounds or disease, who were unable to bear removal. Three Yankee women and eight Yankee deserters, or rather men who came over to us and professed to be such, were sent from Castle Thunder. Though these deserters professed to have left their brethren in great disgust, they were very willing to be sent back to the North. The departure of the prisoners will save the Confederate Government an expense of about $4,000 per day, which was the average that their food as soldiers cost.
Casper returned to the Regiment on either November 15 at Alexandria, Virginia, or December 20, 1862, at Camp Pitcher, Virginia.
He reenlisted on December 21, 1863, at Brandy Station, Virginia, crediting Grand Rapids’ 4th Ward, was presumably absent on veteran’s furlough in January of 1864 and probably returned to the Regiment on or about the first of February. He was transferred to Company I, Fifth Michigan infantry upon consolidation of the 3rd and 5th Michigan Regiments on June 10, 1864, and again taken prisoner on December 6, 1864, at Jerusalem Plank road, near Petersburg, Virginia. Thenner was sent from Petersburg to Richmond on December 10, 1864, and paroled at Cox’s Wharf, Virginia on February 5, 1865.
Casper was subsequently furloughed as a paroled prisoner of war, and soon afterwards returned to Grand Rapids, where he was examined by Dr. Charles Hempel. Dr. Hempel certified on March 20, 1865, that Thenner was “suffering from chronic diarrhea and general debility and is not able to travel and I further certify that in my opinion he will not be fit for duty in less than twenty days.”
In fact, Casper died in Grand Rapids of chronic diarrhea on May 27, 1865, and was reportedly buried in the “city cemetery” (presumably in Fulton Cemetery), although all traces of his grave have disappeared.
“Casper Thener,” wrote the Eagle on May 31,
“a veteran number of company C, Captain Theodore Hetz, in the old Third Mich. Inf., was buried in the city cemetery on the 29th inst. Young Thener went out with the glorious Regiment and remained in its ranks through all the terrible battles it passed, reenlisted, and was, with the comparatively few left at the time, merged into the 5th Mich Inf. While in that command and in an engagement before Petersburg, he was taken by the rebels and remained a prisoner until paroled, when he came home a few months since, a victim of a disease which terminated his life. His funeral was attended and the remains followed to the grave by a company, under command of Captain [Theodore] Hetz, of heroes, once members of the the old Third. In the funeral procession were carried two battered and torn battle flags -- sacred relics of that once proud command.”
There is no pension file available.