The unique approach Mark H. Dunkelman has taken to Civil War history dates from his childhood, when his father and aunt passed along stories and relics of their grandfather, with whom they had grown up on a farm in Cattaraugus County, New York. Those tales and mementoes of Corporal John Langhans of the 154th New York Volunteer Infantry gripped Mark with a life-long passion to learn more about his great-grandfather's regiment.

During a lifetime of study, he has had the good fortune to connect with more than 1,200 descendants of members of the 154th New York. Since 1986, Mark has organized annual reunions of the descendants in Cattaraugus and Chautauqua counties, where the regiment was raised. In 1996, he led them in raising funds and erecting a monument to their ancestors at Chancellorsville, Virginia, the 154th's bloodiest battlefield. In five decades of work, Mark has located and copied more than 1,700 wartime letters, 27 diaries, portraits of more than 260 members of the regiment, and a great mass of other material. These sources became the basis for his six well-received books and dozens of articles on various aspects of the 154th's history. His work is preserved in a collection of regimental materials at St. Bonaventure University.

In addition to Civil War history, Mark has had two other lifelong passionate pursuits. He plays pedal steel guitar and dobro and sings in a band, Clip Clop, which performs his own compositions. And since childhood he has created artwork. Gettysburg's Coster Avenue tells the story of his crowning artistic achievement: The Coster Avenue Mural depicting the 154th New York in action on the battle's First Day, at the very site on which it occurred.