William Hartman moved with his parents to Clarion County in 1840. He owned a farm in Mt Airy, near Callensburg, Clarion Co, PA. The farm was in an area known as Hartman's Corners. He joined Regiment 155, Co H of the PA Volunteers on 22 August 1862. His name is on the PA monument at the Gettysburg battlefield. Participated in Gettysburg, Battles of Fredericksburg, Chancellorsville, and Wilderness. Mustered out 2 June 1865 at Washington, D.C. Distinguished Service. References include obituary, tombstone and Civil War Pension papers.

From Rimersburg Gazette, date unknown
My Trip To Gettysburg
Editor Rimersburg Gazette
I wish to tell your readers something about our trip to the famous battle field of Gettysburg. The survivors of all the Penna Regiments that participated in said battle in 1863 were accorded free transportation to and from Gettysburg, to view the historic ground on which we fought the rebels in the long ago, and also to witness the dedication of the imposing memorial, erected on the battlefield by the state, at a cost of $150,000.
We therefore availed ourselves of this opportunity and in order that we might be conveyed thither, we took passage on the south bound train at Lawsonham on Saturday morning, Sept. 24th, arriving in Gettysburg in the evening of the same day.
Gettysburg is rather a nice town, having a population of 40,000. The number of veterans and visitors was estimated to have been equal to 24,000. Many private homes opened their doors to receive the veterans and their friends, so that the enormous crowd was all provided for. The monument was, on Tuesday, dedicated in the presence of an assemblage numbering about 12,000, 4,000 of which were veterans of the civil war.
In our rambels over the battlefield the writer located and go on top of the identical rock upon which he slept one night at the time of the battle. The reason for this elevated spot was to keep out of the water, (the ground being very wet with a drenching rain.) In the National cemetery (which is very beautiful) repose the bodies of 3555 of our brave comrades.
This battlefield is indeed an interesting place to visit, but yet it is sad and solemn to think that all this is the result of war. We shudder at the thought of war and blood shed, and our hope and prayer is that it may be forever hereafter averted.
In all probability this trip to Gettysburg will be our last one, however we enjoyed it very much, and reached home in safety.
Yours Truly
W. D. Hartman

From local paper, name (most likely the Rimersburg Gazette) and date unknown (but would be August 1913):
WILLIAM D. HARTMAN
After several months of failing health in advancing years, death claimed William D. Hartman of Squirrel Hill, Porter township, this county August 2nd, 1913. He was a most amiable and respected citizen, a soldier of the Civil War and a Christian gentleman. He was born in Columbia county, Pa., August 10th, 1836, and lacked only eight days of being seventy-five. He came with his parents, John W. and Susan (Fulmer) Hartman to Clarion county in 1840. They settled on a farm at what is known as Hartman's Corners, or Mt. Airy. On this farm he spent his childhood and young manhood days learning the blacksmith trade. When the war of the rebellion broke out he enlisted in the Union army, August 1862, and was one of the original members of Comapny H, 155 Regiment Penna. Vols., participating in the great battles of Frederickburg, Chancellorsville, Gettysburg, Wilderness and numerous other engagements until the close of the war.
He then returned home to his widowed mother, the father having died in 1848, and worked at the blacksmith trade for fifteen years. In 1868 he was married to Miss Francis Snyder of Salem township. To them were born two sons and five daughters, the youngest of the latter dying at the age of fourteen. Mrs. Hartman died December 13, 1909. He is now survived by the following sons and daughters: Frank H. of Squirrel Hill; John A., Effie, Laura and Ida, of Rimersburg; Mary, of New Kensington, and three brothers, Josiah, of Sligo; Jackson, of Curllsville; Aaron, of Clarion, and one sister, Rebekah, of Sligo.

History of Clarion County, Chapter XXXII, p 319, Comapny H, ONE HUNDRED AND FIFTY-FIFTH REGIMENT P.V. :
No company in the whole number of Clarion county companies deserves a higher place in the estimation of the reader than Company H, of the One Hundred and Fifth-fifth. It was recruited at Rimersburg, by Professor John Ewing, in August, 1862, and was mustered into the United Sates service August 22, 1862, being designated as shown by title and assigned to the Second Brigade, Third Division of the Fifth Corps. It proceeded to the field by way of Kittanning, Pittsburgh and Harrisburg to Washington. The Regiment went into the field at once, lying in reserve at Antietam. At Gettysburg it did magnificent service as noted under "Company G".
At Petersburg the regiment lay in reserve on the 16th and 17th. On the 18th the Fifth Corps relieved the Ninth Corps in the morning and moved upon the enemy, capturing a cut in the railroad, the One Hundred and Fifty-fifth occupying a position about the center of the corps. At five P.M. a charge was ordered, and the troops moved forward under the most fearful and destructive fire that ever greeted braven men on a mission of death. In this terrible ordeal, Company H lost twenty-two men in killed and wounded...
CORRECTED ROLL OF COMPANY H, ONE HUNDRED AND FIFTY-FIFTH REGIMENT, p. 323:
Hartman, Wm. D., private, August 22, 1862; three years; mustered out with company June 2, 1865.
Hartman, Lewis, private, August 22, 1862; three years; mustered out with company June 2, 1865.