PITTSBURGH (KDKA) — Lawrenceville was rocked by three powerful explosions on Sept. 17, 1862.

The 150th anniversary of the Allegheny Arsenal tragedy will be commemorated Sunday, with a special presentation at the site. CLO Academy students will play the roles of Irish workers, killed by the blast. Their backdrop is the powder magazine, the only structure to survive the explosions.

“It’s reported to be the largest single day loss of civilian life in the Civil War,” says Mary Frailey Calland, author of a historical novel called “Consecrated Dust.” She recalls the day 78 workers, mostly women and girls, lost their lives.

Forty-five unidentified remains were buried in a mass grave in Allegheny Cemetery. The cause of the tragedy is still unknown, though one theory blames a horse and wagon.

“A spark from the horse’s hoof,” says the author, “or perhaps from the steel bands that surround the wheel of the wagon, ignited powder in the stone roadway. That that powder made its way to some powder kegs at the end of the porch.”

The arsenal covered 30 acres, all the way from Penn Avenue to the Allegheny River. Much of where it once stood is now open space, the site of Arsenal Park.
Sunday’s commemoration at the park begins at noon. Mary Frailey Calland will sign copies of her book.

“It was a great sacrifice by the people of Pittsburgh and these families,” the author concludes. “And I hope people will remember that.”

For more information on the book, “Consecrated Dust,” log onto: http://www.maryfraileycalland.com .