Members of the Weather Underground (Weathermen), an American leftist militant group, were making bombs in the basement of 18 West 11th Street in the Greenwich Village neighborhood, when one of them exploded.

The resulting series of three blasts completely destroyed the four-story townhouse and severely damaged those adjacent to it, including the then home of actor Dustin Hoffman and theater critic Mel Gussow.

Three Weathermen—Ted Gold, Diana Oughton and Terry Robbins—were killed in the blast, while two survivors, Kathy Boudin and Cathy Wilkerson, were helped out of the wreckage and subsequently fled.

[1][2] Responding firefighters initially believed the blast to have been an accidental gas explosion, but police suspicions were aroused by the two survivors' apparent disappearances, and by that evening other bombs the Weathermen had built were found.

They had been meant for several targets: a noncommissioned officers' dance at Fort Dix in South Jersey that night, and the administration building at Columbia University.

After their bail in the Chicago case was revoked when they failed to show up for trial shortly after the explosion, Boudin and Wilkerson remained fugitives from justice for a decade.

[2] Boudin eventually was apprehended in 1981 and pleaded guilty to felony murder and robbery in the Brink's case in exchange for a sentence of 20 years to life in prison.

At that meeting, the Weathermen, who had taken their original name from the line "You don't need a weatherman to know which way the wind blows" in Bob Dylan's 1965 song "Subterranean Homesick Blues"[3] had discussed what actions they might take, and against what targets.

The consensus was that the police and the military were legitimate targets, representing the urban racism that their allies the Black Panthers most strongly opposed, and the Vietnam War.

[4] After the meeting, the Weathermen split into three groups, based in San Francisco, New York City and the Midwest, under the leadership of Howard Machtinger, Terry Robbins and Bill Ayers respectively, to plan and carry out bombings.

Machtinger's group carried out the first Weather Underground bombing, with explosives detonating shortly after midnight on February 13, 1970, during shift change at the Berkeley, California, police headquarters.

When he learned from Cathy Wilkerson that her father, a radio executive[7] with whom she had a difficult relationship, would be away from his Greenwich Village townhouse for several weeks while he vacationed in St. Kitts with her stepmother, he asked her if she could get the key so the Weathermen could have a central place to work from.

She told her father, who was planning to sell the house soon so he and his English-born wife could move back to her native country,[2] she needed a place to recuperate from the flu, and he gave her the key.

[4] After a meeting they designated three targets, including a noncommissioned officers' dance at Fort Dix, which was due to take place on March 6.

It was reported that "arguments went on day and night" in the townhouse, with Kathy Boudin advocating that they kill as many people as possible with anti-personnel bombs.

A few minutes later, she heard a dull roar from the basement and watched as the carpeted floor broke in several places beneath her, letting through a red glow as shards of broken wood and plaster erupted from it.

Wilkerson regained awareness and heard Boudin nearby on the edge of what was now a crater in the basement; the two were able to link hands and escape just as a fire built up behind them.

[7] They initially thought that had been the cause, but a police detective on the scene called Albert Seedman, his superior, and said it seemed unnaturally destructive for a gas explosion.

That night, with enough of the fire out to enter the site, Gold's crushed body was found; after his identity was confirmed two days later, students at Columbia University, his alma mater, tried to lower a flag on campus to half-staff in his memory when they heard the news.

[2] On the morning of March 10, Oughton's mutilated and dismembered remains were uncovered; she had been shot through with the roofing nails intended to be packed with the bombs as shrapnel.

[14] Investigators described the building as a "bomb factory" and said the bombmakers were evidently wrapping dynamite in tape with nails embedded to act as shrapnel at the time of the explosion.

"[14] The search for bodies continued for nine days after the explosion, and at Seedman's suggestion Wilkerson's parents made a televised appeal to their missing daughter to avoid needlessly risking the lives of searchers.

Fingerprint records were required to identify the dismembered remains of Gold, a leader of the Columbia University protests of 1968, and Oughton, the organizer of the 1969 SDS national convention.

[16][17][18][19] Rumors circulated among leftists that the third body was that of Robbins, a leader of the 1968 Kent State University student rebellion and a founder of the Weathermen, who would be indicted the following month along with 11 others for organizing and inciting riots during the Days of Rage.

In May, after the remaining members gathered in San Francisco to confer, Bernadine Dohrn issued a statement in the name of the group declaring war on America, warning that they would "attack a symbol or institution of American injustice" within the next two weeks, and confirming that Gold, Oughton and Robbins had been among its membership.

I wasn't afraid of [dynamite]; I knew it could be handled", he told journalist Bryan Burrough, who called him the Weathermen's "unsung hero", in 2015.

Wilkerson surrendered in 1980 and served 11 months of a three-year sentence on the dynamite possession charge, the only criminal prosecution resulting from the explosion.

[22] Weather Underground leadership members Bill Ayers, Bernardine Dohrn, and Jeff Jones have claimed the planned bombings of the Fort Dix NCO dance and the other plan to bomb a Columbia University building were a rogue operation led by more extreme Greenwich Village townhouse residents; Ayers singled out Terry Robbins.

[26] James Merrill, the poet who had lived in the house as a young child, lamented the bombing in his 1972 poem "18 West 11th Street", contrasting his own opposition to the war with what he believed to have been the Weathermen's vain decision to oppose it violently and destroying his childhood home along with themselves in the process.

After eight years in which he was unable to do so, he sold the property at cost to David and Norma Langworthy, a Philadelphia couple looking for a retirement home in the neighborhood where they had lived as newlyweds on the condition they build the house he had designed.