December 1969 marked a very important month for the Weathermen. It was in December that Frank Hampton, a member of the Black Panthers, was murdered in his own apartment during a police raid. It is still unknown to the public weather Hampton's death was premeditated or the police had to shot Hampton to save his own life. The Weathermen believed that the whole ordeal was premeditated and the cops knew they were to go in and kill Hampton.
December 1969 marked the time that a select few of the Weathermen dropped out of society and went "underground" and went by "The Weathermen Underground" from then out. They were fed up with their injust and corrupted government and decided to take the demonstrations to the next level. The Weathermen Underground planned to overthrow the government with a set of carefully planned bombings over the next 11 months. The bombs were usually planted somewhere of political signifigance, where they could get what they believed was revenge. (Note that the Weathermen never intended to harm a human being with these bombings. They would call in an hour prior to detonation to make sure that everyone would safely evacuate the building. They were trying to overthrow the government, not murder innocent bystandards).
The Weathermen Underground started with a bombing of a New York City judge who was involved with a case over the Black Panthers. Maybe this was a revenge of sorts for the murder of Frank Hampton? Another bomb was set off in a bathroom in the Pentagon after President Nixon ordered for a series of bombings in North Vietnam. A bomb was also detonated at New York State Department of Corrections after the Attica Prison riot.
Fatefully on March 8 1970, three members of the Weathermen Underground were killed in an explosion in James Wilkerson's (his daughter Kathy Wilkerson was a member of the "Underground" and allowed fellow members to use her father's home to make the bomb) home in Greenwich Village, NY while they were trying to make a bomb. These victims were Diana Oughten, Ted Gold, and Terry Robbins.
In September 1970 the Weathermen Underground sucessfully helped acid-guru of the 1960's Timothy Leary escape from prison and let him come into hiding with them.
Timothy Leary's escape from prison was really the last we heard from the Weathermen. Every couple of years those who were brave enough would resurface back into society. Some of those lucky enough to go unnoticed and slip back into their own lives and some being caught and put up against the US judicial system, the very system they despise so much.
The unofficial end of the Weathermen was in 1981 when Kathy Boudin comes out of hiding to commit armed robbery in Nanuet, New York. The end result is the death of three men. Boudin was sentenced to 22 years in prison and recently released last year.