April 3, 1913 - Pietro Botto, socialist mayor of Haledon, N.J., invited the Paterson silk mill strikers to assemble in front of his house. 20,000 showed up to hear speakers from the Industrial Workers of the World (IWW), Upton Sinclair, John Reed and others, who urged them to remain strong in their fight. (From Work Day Minnesota)
The Patterson strike lasted from Feb. 1 until July 28, 1913. Workers were fighting for the eight-hour workday and better working conditions. Over 1800 workers were arrested during the strike, including IWW leaders Big Bill Haywood and Elizabeth Gurley Flynn. Five were killed. Overall, the strike was poorly organized and confined to Paterson. The IWW, the main organizer of the strike, eventually gave up. (From the IWW: Its First Seventy Years, by Fred Thompson and Patrick Murfin).
April 3, 1917 – U.S. declared war and sailors, escorted by police, destroyed the IWW building in Kansas City. The action inspired similar attacks in Detroit, Duluth and other towns that had a large IWW presence. (From the Daily Bleed)
April 3, 1948 – Cheju Massacre in Korea. Between1948 and 1949, one of the 20th century’s least known genocides occurred. On the island of Cheju-do, 30,000 civilians were massacred (10% of the island’s population) by the South Korean army, Cheju-do police and the U.S. military, in the name of fighting communism. However, the governor of Cheju told American intelligence that the real number was closer to 60,000. (From the Daily Bleed, with more information here and here.)