The Black Panthers were street thugs pure and simple. Marxism was simply another hustle for them. They ended up killing several of Horowitz's associates and that is what drove him to reject the Left. I think the Symbionese Liberation Army was driven in large party by nihilism, not to mention hatred of the white race. This is also true of the Weather Underground, their intense hatred of the white race led them to kill people and attempt to destroy the South. Here are some quotes.
I also interviewed Mike Rudd, who had led the "uprising" at Columbia in 1968 and been purged from the Underground after the town house explosion. I found him in Albuquerque, where he was teaching at a technical college. A large, affiable man, Rudd alone among the leaders I interviewed had a basic honesty about himself and was feeling a genuine remorse for the wasted and destructive years he had spent in the Weather army. He told me that the tragedy in which the three activists had died was caused by a bomb they were preparing for a service-club dance at Fort Dix. This was the first information about their planned target that anyone had revealed, and it produced a shock of recognition in Peter and me. The three bombers were SDS veterans; their intended targets - young people at a dance - showed just how malevolent the Movement had become. Chastened by the loss of their comrades when the plot misfired, the Weather leadership later confinded its targets to such symbolic venues as the U.S. Capitol building, where Bernadine and Kathy Boudin - who had narrowly escaped the town house explosion - planted a bomb in the ladies room.
Rudd also helped us to piece together the bizarre final acts of the [Weather] Underground, which had initiated a series of purges in its ranks, complete with confessions and recantings - a farcical replay of the revolutionary past. The purist remnant that conducted the purges subsequently joined elements of the Black Liberation Army, to form the May 19 Communist Organization - celebrating a date which marked the birthdays of Malcolm X and Ho Chi Minh. The goal of these revolutionaries was to create a "New Afrika" in America's southern states, through a campaign of guerilla war. To finance this war, the group held up a Brinks armored car in Nyack, New Jersey. This led to a gun battle in which three policemen were killed, including the only black officer on the Nyack police force. The perpetrators - Kathy Boudin among them - were given 20-year sentanes, ending their political careers.
Experienced as I was in the Left, I found it difficult to understand the mentality behind such acts. It as the fourth year of the liberal Carter Administration: the Vietnam War was over; Andrew Young, a black Sixties radical, was America's ambassador to the United Nations; Selma, Atlanta, and many other citadels of the segregated South had black mayors and police chiefs; and the entire South had undergone a political and cultural revolution as dramatic as any modern society had ever achieved. What could justify or inspire such strategies of rebellion. Why declare war on "Amerika" now?
-- David Horowitz, [b:53a1f1121b][u:53a1f1121b]Radical Son[/b:53a1f1121b][/u:53a1f1121b], p.334