On December 3, 1969, 21-year-old Fred Hampton, the chairman of the Illinois chapter of the Black Panthers, led a political education class, had some dinner, and talked to his mom on the phone. He passed out around midnight, still on the phone with her.

At about 4:45 a.m., the Cook County police department burst into the Panther headquarters. They shot 18-year-old Mark Clark, who was on security detail, in the chest, killing him instantly. They sprayed close to 100 rounds as they swept through the apartment, heading for Hampton’s room, where he was sleeping with his pregnant fiancée. His fiancée and another man heard the gunshots and tried to wake Hampton up, but they couldn’t. The police charged into Hampton’s room, dragging his fiancée and the other man out.

“He’s still alive,” they overheard an officer say. They said they heard two shots, and a second officer said, “He’s good and dead now.” They’d shot Hampton point blank in the head.

Years later, it was revealed that Hampton’s bodyguard, William O’Neal secretly worked for the FBI. He’d been coerced into becoming an informant in exchange for getting criminal charges dropped. O’Neal had given the cops a map of the apartment that helped them locate Hampton in the predawn raid. It’s long been suspected, but not confirmed, that O’Neal had also drugged Hampton ahead of the raid. Years later, O’Neal killed himself.

Hampton’s killing was part of the FBI’s secret COINTELPRO program. COINTELPRO targeted members of the Black Panther party and other leftist groups in the 1960s and early 1970s, surveilling and infiltrating them to sow discord. “COINTELPRO was designed to destroy black liberation organizations starting with Dr. Martin Luther King Jr. and Malcolm X,” Flint Taylor, the civil rights lawyer who fought in court to expose the facts about Hampton’s killing and the existence of COINTELPRO, told Teen Vogue. FBI head J. Edgar Hoover, who started the program, worried that a black “messiah” would electrify the movement for black rights.

In Chicago, at the age of just 21, the charismatic Hampton had realized Hoover’s fear, starting a number of popular programs, including a free breakfast program. He also founded the Rainbow Coalition, an alliance uniting poor blacks, poor whites, and Latinos. The Panthers organized with the Young Lords Organization, a Puerto Rican group, and the Young Patriots Organization (YPO), comprised of poor white migrants from Appalachia.

Hampton and other Panthers, like section leader Bobby Lee, made the case that, as poor people trying to survive in Mayor Richard J. Daley’s racially segregated city, they had more in common with each other than not. They banded together to protect members from the cops, fight against police brutality, run health care clinics, feed the homeless and poor kids, and connect people with legal help if they were dealing with abusive landlords or police.

“We did security for the Panthers along with other Panthers,” 70-year-old Hy Thurman, a member of the YPO, told Teen Vogue from his home in Alabama. “Here’s a bunch of hillbillies doing, you know, security for black people and Black Panthers,” Thurman said. “That was shocking for a lot of people.” Out of respect for the Panthers, the Young Patriots — which grew out of a street gang called the Peace Makers — decided to stop wearing the Confederate flag.

Meanwhile, the Young Lords foregrounded issues impacting immigrants from Latin America and citizens who moved from Puerto Rico, birthplace of cofounder Jose “Cha Cha” Jimenez. The introduced the slogan, “Tengo Puerto Rico en mi corazón," in the fight for Puerto Rican self-determination.