16 SEP--This Day in US Military History

1920 – As lunchtime approached on September 16, 1920, New York’s financial district was grinding through its regular motions–people were gathering outside to eat, and brokers were holed up inside, busily trading away the day. But before the clock hit noon, routine gave way to panic, as a horse-drawn wagon filled with explosives suddenly detonated near the subtreasury.

Flames flooded Wall Street, shooting up nearly six-stories-high. The blast shattered windows around the area and sent a pipe crashing against the neck of a man strolling some six blocks away from the subtreasury. All told, 300 people were killed and a hundred more were wounded. The only famous financial figure to be injured was Junius Spencer, J.P. Morgan’s grandson, who suffered a slight gash on one hand.
Since radical bashing was in vogue at the time, Communists, Anarchists, and anyone else leaning too far to the left were accused of having staged a violent protest against capitalism. More pragmatic souls argued that the wagon belonged to an explosives operation and had simply strayed from its prescribed route. Whatever merits these theories have, the ensuing investigation failed to uncover the culprit or cause of the blast, and the case remains a mystery.

https://thisdayinusmilhist.wordpress.com/2014/09/16/september-16/