
Date: May 04, 1886

The first flier calling for a rally in the Haymarket on May 4. and the revised flier for the rally later, the words “Workingmen Arm Yourselves and Appear in Full Force!” were removed from the revised flier.
wiki/Haymarket_affair
(1886) Workers strike and rally for rights in major US cities.
Also on this day,
1776 | Illuminati begins
1851 | Great Exhibition starts
1931 | Empire State Building opens