17th September 1862: Allegheny Arsenal explosion, American Civil War's largest civilian loss of life

The Allegheny Arsenal in Lawrenceville, just outside Pittsburgh, was originally built in 1814 and was a critical part of the U.S. Army supply chain in the west. The Arsenal was spread out across more than 30 acres in a complex that manufactured gunpowder, cartridges, harnesses, and other valuable equipment critical to the war effort.
Around 2pm on 17 September the first of three explosions brought the commander of the Arsenal, Colonel John Symington, rushing to the site. The blasts flattened buildings and scattered debris across the surrounding Lawrenceville neighbourhood. The shockwaves were felt far beyond the Arsenal's walls, and the noise could be heard over 2 miles away in Pittsburgh itself. Although locals brought fire-fighting equipment and organised a bucket brigade, the fire wasn’t brought under control until the volunteer fire company from Pittsburgh arrived.
More than 1,100 people worked at the Arsenal, 78 of whom died while many more were injured. This makes the Allegheny Arsenal explosion the single largest civilian disaster of the war. Many of the casualties were teenage women, and some of the bodies were so badly disfigured by the blast that they were unidentifiable and had to be buried in a mass grave.
The cause of the explosion has never been conclusively proven, although the most commonly-held view is that a horse’s metal shoe struck the road outside and caused a spark that ignited loose powder which travelled to the Arsenal itself and ignited the large stores.

[@minibus9]

excelnt video, respesctfully done