Karl Reisner, a Mercersburg Academy legend who spent 44 years on the faculty as a history teacher and built the school’s baseball program into a true dynasty, passed away July 21, 2026, in Richmond, VA. He was 77.

Born June 3, 1949, Reisner grew up in Allentown, PA. His grandfather, Karl L. Reisner, attended Mercersburg as a postgraduate student and was a member of the Class of 1905. While the younger Reisner enrolled at and graduated from Mercersburg’s historic rival The Hill School, in a poetic bit of foreshadowing, Reisner’s first hit as a varsity baseball player came on the Mercersburg campus in a game against his future employer. 

Reisner matriculated at the University of Pennsylvania, where he earned All-America honors in sprint football for the Quakers while serving as team captain. He graduated in 1971 and, though he originally intended to go to law school, ultimately chose to join the Mercersburg faculty that fall. Reisner later completed a master’s degree from Lehigh University.

In addition to history, Reisner taught English for part of his Mercersburg tenure. He will be remembered as a stalwart not just in the classroom but also on the fields of play, where he coached wrestling, football, and girls basketball, along with baseball. Reisner spent 24 years as head varsity baseball coach, and his 356 victories in the sport are a school record. His teams won 16 conference titles on the diamond (including the first five in a run of eight consecutive Mid-Atlantic Prep League championships or co-championships from 2011 to 2018) and four Pennsylvania Independent Schools Athletic Association state championships.

“This place means everything to me,” Reisner said in a 2015 issue of Mercersburg magazine. “My faith, my family, and my job have been the three things that are central to my life. I have been privileged and proud to be a part of the development of this place.”

Reisner served in several additional roles at the school over the years, including as dorm dean of Culbertson House, head of the history department, and in the offices of college counseling and summer programs. Reisner’s influence was so significant that two former students, Lacy Rice III ’79 and Brooke Kinney ’79, established the Karl Reisner Scholarship Fund in his name, a testament to his lasting impact in education. He held Mercersburg’s Archibald Rutledge Chair from 1992 to 2001 and the Marilyn and Robert M. Kurtz ’52 Chair for American Studies from 2001 until his official retirement from the faculty in 2015. For a couple of years after retirement, he continued to teach AP sections of U.S. history and European history at the school.

Reisner was a longtime member of the Mercersburg Rotary Club and Tuscarora Jaycees, and was involved in the Mercersburg Historical Society, Mercersburg Little League, and Saint John’s Lutheran Church Council in the borough. He also portrayed Mercersburg native and President James Buchanan on C-SPAN as part of that television network’s 1999 series on U.S. presidents; he was the only high school teacher selected to participate.

Reisner and his wife, Stephanie, had been married for 44 years before she died in 2017. Survivors include son Kristopher ’94 (and his wife, Juanita), daughter Amanda ’97, and three grandchildren, Matthew, Alex, and Amelia.

Click here to view Reisner’s obituary.