Memorial Day massacre of 1937
1937 CE.
Shown on the map at 41.683°, -87.540°.
In the Memorial Day massacre of 1937, the Chicago Police Department shot and killed ten unarmed demonstrators in Chicago, on May 30, 1937. The incident took place during the Little Steel strike in the United States.
Text from the Wikipedia article 1937 Memorial Day massacre, licensed CC BY-SA 4.0.