After the shooting, dozens of Black Disciples gathered at their home base: the Parkway Garden Homes, a complex of brick mid-rise buildings stretching three blocks along South Martin Luther King Jr. Drive, built in the 1950s to house black middle-class families. Michelle Obama lived there as a toddler.

But over time, the middle-class families left, and mostly low-income families moved in. More than half of the population lives in poverty in Parkway and the surrounding neighborhood, which is 95 percent black. An abandoned Walgreens sits on King Drive, along with cellphone stores and fast food shops that moved in when many businesses picked up and left.

Parkway earned a reputation as one of Chicago’s most violent areas. It was, however, considered a safe zone for the Black Disciples who controlled the complex — a faction known as O’Block, named after a fallen ally, Odee Perry.

Now they were debating how to respond to the shooting at New Food.

Some people wanted to respect the truce, in large part because it allowed them to make money by selling drugs in peace. That was why many had advocated for it in the first place.

Others, however, turned to the man who had been shot, Kaos recalled.

“We’re with whatever you’re with — however you feel about it because you got shot,” he recalled some people saying. “If you want to push, we’re going to push.”

Black gangs began sprouting in Chicago in earnest in the 1950s during a second wave of northward migration of black Southerners. The migrants came looking for opportunity, but were crammed into overcrowded, segregated pockets on the city’s South and West sides where industry and jobs were dwindling.

Conditions were ripe for what followed: Boys, with little supervision, money or education, formed cliques. They hung out socially, and got into fights and other petty trouble.

The rabble-rousing evolved into extortion of local businesses, much as it did with the existing white ethnic gangs and local mobsters. Then came the heroin and crack epidemics that turned gangs into lucrative drug-trafficking organizations that fought over territory. For a while, though, the gangs in Woodlawn also helped keep calm and avoid riots after the assassination of the Rev. Dr. Martin Luther King Jr. and helped with a federally funded job training program in the area.

But those highly organized operations have fizzled over the last 25 years as prosecutors swept up gang leaders, and the city demolished public housing projects, dispersing gang members primarily to minority neighborhoods on the West and South Sides.

Now they were everywhere and nowhere — gangsters by name, but kings only of corners and blocks.

And instead of turf and money, they fought over personal slights.

Kaos was coy about how O’Block responded to the shots fired by the Jaro City member at New Food. Violence did, however, continue that week.

Two days after the New Food shooting, two Gangster Disciples were shot at night in a drive-by about a block from the store, but people on both sides said that particular shooting was unrelated to the feud.

A day later, the two sides clashed again near New Food, firing shots at each other. The mother of a Black Disciple was caught in the crossfire, shot in her left foot.

By late that afternoon, Sept. 22, alarm bells were going off at New Beginnings Church. Pastor Brooks huddled with some of the gang elders. The truce seemed to be falling apart.

Lavondale Glass, 43, a former Gangster Disciple who was helping to broker peace, saw the young men falling into the dangerous logic of revenge.

“This is what I don’t understand with the younger generation,” Mr. Glass, who goes by the name Big Dale, told Kaos one day. “How could you honor the dead and not the living?” Those who were killed are dead, he said. “Ain’t no bringing them back.”

Big Dale had lost his own father, Leon Holton, in 1996 — assassinated in a Gangster Disciple power struggle as federal agents were moving hard against many of the gang’s top lieutenants. His son, who is part of the Jaro City faction, was shot in the hand a few days before the truce was brokered.

But there often comes a time when the gang members lucky to make it past their 30s face the damage they have done and want to fix it. Big Dale had reached that point.

Pastor Brooks and the elders decided that Big Dale would gather the Gangster Disciples to discuss what was going on, while the Black Disciple old heads would do the same with their side. They would then hold a joint session to determine how to get the peace back on track.

But after the Black Disciples spent about an hour shouting at one another in a parking lot behind the church, the elders realized they first needed to resolve an internal rift. It appeared that some in the O’Block clique were jealous because, while they were broke, their allies from the 63rd Street faction seemed to be making money selling drugs, said a former Black Disciple who described the issue only on the condition of anonymity.

​The attitude of some of the young men on O’Block was that if they couldn’t make money, then “can’t nobody get nothing,” the former Black Disciple said. “When they get bored, they do stupid stuff.”