De Leon, Daniel at English => English (The Britannica Concise) Of Explained:
U.S. (Dutch-born) socialist. Born in Curaç ao, he arrived in the U.S. in 1874. He joined the Socialist Labor Party in 1890 and soon became one of its leaders. Finding the labor union leadership insufficiently radical, he led a faction that seceded from the Knights of Labor in 1895, later forming the Socialist Trade and Labor Alliance (STLA). In 1905 he helped found the Industrial Workers of the World (IWW), which absorbed the STLA. In 1908 his leadership was rejected by extremists who favored more violent forms of political activity, and he created the unsuccessful Workers' International Industrial Union.