Preparedness Day bombing

You are standing near the intersection of Market and Steuart Streets, the site of the deadliest act of terrorism in San Francisco history. On the afternoon of July 22, 1916, this corner became a scene of absolute carnage during a massive parade organized to advocate for American entry into the First World War. A suitcase filled with dynamite and nails detonated just after two o'clock, killing ten people and wounding forty others. The explosion occurred while over fifty thousand marchers were parading through the city streets. In a chilling display of the era's priorities, the event continued even after the blast, with participants marching over the debris and blood-stained pavement. Investigators later discovered that the streets were washed down almost immediately, destroying the scene before forensic evidence could be collected. While no perpetrator was ever captured, the bombing provided local business leaders with a convenient pretext to target labor activists. Two local organizers, Thomas Mooney and Warren Billings, were arrested and convicted based on perjured testimony and fabricated evidence provided by detectives working for private utility interests. The two men spent over two decades in prison before they were finally exonerated and pardoned. To this day, the identity of the person who placed that suitcase remains one of the city's most enduring mysteries.