Video: 'Tom Mooney & the Preparedness Day Bombing'

(Saturday, July 22, 1916, 2:06 p.m. local time) — 10 people were killed and 40 others wounded today when a suitcase bomb went off during San Francisco’s Preparedness Day parade, an event sponsored by the local Chamber of Commerce in anticipation of America’s entry into World War I.

Video: 'UNSOLVED: Preparedness Day Bombing'

Two anti-war labor leaders, Thomas Mooney and Warren K. Billings, were convicted of the bombing and imprisoned, but were released in 1939 amid doubts about their guilt.