Arsenal explosion: Another tragedy on September 17, 1862

The site of the old Allegheny Arsenal is now Arsenal Park.

Only remaining building from the old Allegheny Arsenal.

A tablet commemorates the Allegheny Arsenal tragedy.

On Sept. 17, 1862, the bloodiest day of the Civil War was fought in farm fields and woodlots in Sharpsburg, Md. More than 3,500 Yankees and Rebels died at the Battle of Antietam. Meanwhile, 140 miles away near Pittsburgh a much lesser-known tragedy rocked the North at about 2 p.m. that day. Seventy-eight people, mostly Irish women and girls as young as 10, were killed in explosions in Lawrenceville at the Allegheny Arsenal, which supplied the Union army with ammunition and more.
  The dead were "lying in heaps," the Pittsburgh Post-Gazette reported the next day about what was the biggest loss of  civilian lives during the war. Eleven days after tragedy, Rev. Richard Lea of the Lawrenceville Presbyterian Church preached:

"The uncertainly of human life was never more strikingly shown in this community than upon the memorable 17th day of September, 1862. The morning was calm and beautiful, and until noon nothing unusual occurred at the Allegheny Arsenal. It was pay day, and the noble Union girls who had toiled all the month, were rejoicing over the reception of the fruits of their labor. The shop had been swept, and among the leavings, some loose powder was scattered over the stony road winding around the beautiful grounds. A wagon was passing, when either the iron of the wheel or a horse's shoe struck fire. In an instant, a terrific explosion was heard, shaking the earth, and inflicting injury upon the surrounding buildings. Amidst a dense column of smoke and a bright sheet of flame, were seen fragments of the building mixed with portions of the human frame, raising high into the atmosphere, and then falling in a horrid shower all around."

There's not much to see today at the site, now called Arsenal Park in the Lawrenceville section of the city. A historical sign along busy 40th Street briefly notes the significance of the Arsenal but doesn't mention the tragedy. On the only remaining Arsenal building, a plaque defaced by graffiti mentions the "mysterious" Civil War tragedy, which may have been the result of negligence. The old stone structure is now used as a maintenance building and restroom at Arsenal Park. 

Coverage of the disaster in the Pittsburgh Post-Gazette on Sept. 18, 1862.