Paul Burton, a retired British commando, was in Washington, D.C., recently to brief a group of journalists on how they might survive a week in Cleveland. “Don’t wear black,” he said. “You don’t want to look like one of those anarchist photographers.” Burton took part in the invasion of the Falkland Islands and ran operations in Northern Ireland. He is now the training director for Global Journalist Security, an outfit that specializes in preparing reporters and aid workers for hostile environments. That often means war zones like Afghanistan and Iraq, but Burton, having noted the scuffles that have been breaking out at Donald Trump’s rallies, designed a new course specifically for journalists covering the upcoming Conventions in Cleveland and Philadelphia.

“Trump’s supporters have been primed to be aggressive,” Burton told the five journalists (all of whom asked to remain anonymous), in a warehouse north of town. They had each paid $1,195 to take the course. A bookshelf next to Burton contained titles on ballistics, dirty wars, and battlefield medicine. He went on, “We’ve got a feeling something may happen, especially if Trump doesn’t get what he wants.”

Burton clicked through some photographs projected on a wall and paused at an image. “What do you think of that one?” he asked the journalists. It showed the husks of two burned cars on a street in Baltimore, in 2015, following the death of Freddie Gray, with police in the foreground and protesters in the background. “Are we safe?”

A cameraman with curly hair spoke up. “I was about fifty feet behind that. It was not a safe place,” he said.

Another picture from Baltimore showed two men on the ground—a middle-aged Latino and an elderly white man. An African-American man was kicking the Latino in the ribs, while a crowd watched.

“That’s my picture,” a photographer wearing cargo pants and a safari shirt said. A gas mask was strapped to his thigh.

Burton replied, “That’s your picture? Wow! Well done.”

“I’m a little far away,” the photographer said. “I shot this with a 70-200”—a telephoto lens. Burton asked why the men were attacked.

“Wrong place, wrong time.”

Burton pressed: “If they were a different color skin, would they have gotten attacked?” He added, “I don’t like to go down that road, but we do have to think about it.”

Natalie Potell, an E.M.T., explained how to treat burns and breaks, and how to plug a sucking chest wound with a round, super-sticky bandage called a HALO Seal.

“You think duct tape would work in a pinch?” the photographer asked.

“Absolutely,” Potell said.

Before the lunch break, Briana Twigg, a self-defense instructor, demonstrated some jujitsu moves, including one that she called the hitchhike, designed to shake off a grabby aggressor. In March, Trump’s campaign manager, Corey Lewandowski, was caught on video pulling a female reporter’s arm at a rally in Florida.

“It’s amazing how well that works,” said the photographer, who was trying out the hitchhike (thumb up, elbow forward, thumb back to the shoulder) on a colleague.

Twigg urged restraint. “You don’t want to do anything that’s going to get you on Fox News, or CNN,” she said.

Next: a maze called the Old City, in the rear of the warehouse. In one scenario, a mock Trump rally, a tape of Trump’s voice played (“The money that’s being drained out of our economy is enormous”), while six instructors, posing as amped-up supporters, set upon the press. “Get the fuck out of here!” one yelled. Another yanked on the photographer’s camera strap and shouted, “Fucking scumbag!” The journalists retreated to safety.

“You did well,” Burton said. “You’re not going to be able to reason with them. You’re not going to get any good interviews. All you’re thinking of is trying to deëscalate and get the hell out of there.”

Burton set the stage for one of the last, and most elaborate, exercises of the day. “We’re still in Cleveland,” he said. His fellow-instructors, and one instructor’s teen-age siblings, simulated a Black Lives Matter protest outside the Convention. Pro-Trump chanters showed up. Riot police in turtle gear followed. They swung their batons, bashing one “protester” in the head until it oozed fake blood, and then zip-tied the protesters and the journalists.

Afterward, the photographer in the cargo pants said that in real life he probably would have responded differently. He said that, as the police moved in, “I’d be backing way the freak up, and I’d be shooting with the 70-200 until they spun on me and said, ‘Get that guy!’ ” He was sitting on the edge of his chair, gear dangling between his legs. “Then I’d beat feet out of there.” ♦