On this day in 1917 a massive explosion occurred at a recently constructed ammunition plant which was providing ammunition under contract to Canada. Sabotage was suspected at the time but a commission found in 1931 that there was no evidence to support that claim.
The disaster was bad enough but would have been worse but for the heroic act of Theresa Louise "Tessie" McNamara in staying at her post as a switchboard operator and providing notice to each link on the circuit that a fire had broken out and people needed to evacuate. She's credited with saving up to 1,400 lives.
The belief at the time that the explosion was caused by German sabotage contributed to growing American support for entering the war in Europe. Ironically, the Black Tom explosion of that past July had been caused by German saboteurs but that was not known at the time. So the Germans were blamed in the minds of some for an explosion they had not caused, but were not blamed for one which they had.