From Wikipedia, the free encyclopedia:
Weatherman, known colloquially as the Weathermen and later the Weather Underground Organization, was a U.S. Radical Left group consisting of splintered-off members and leaders of the Students for a Democratic Society which formed on the campus on the University of Michigan in the 1960s. (They took their name from a line from the Bob Dylan song 'Subterranean Homesick Blues' "You don't need a weatherman to know which way the wind blows.") The group referred to itself as a revolutionary organization of women and men whose purpose was to carry out a series of attacks that would achieve the revolutionary overthrow of the Government of the United States. Their attacks were mostly bombings of government buildings, executed after calling in bomb-threats and making sure their target buildings were evacuated. The Weathermen imploded shortly after the U.S. withdrawal from Vietnam in 1975, which saw the general decline of the New Left, of which Weatherman had been a part.
Early on, the Weathermen were part of the Revolutionary Youth Movement within the Students for a Democratic Society. When they split — first from the RYM's Maoists and then from SDS itself — they distinguished themselves from other self-proclaimed revolutionary groups by claiming that there was no time to build a vanguard party and that revolutionary war against the United States and the capitalist system should begin immediately. To that end, they carried out one of the first domestic terror campaigns in the United States, consisting of bombings, jailbreaks, and riots."