I met Boertje-Obed in a small visiting room filled with beige plastic chairs. The only other people in the room were a prison official and a corrections officer, both of them polite and friendly and not especially interested in our conversation. Leavenworth is a medium-security facility today. But gang members and murderers are still incarcerated there, amid a prison culture rigidly divided by race. The typical inmate is serving a ten-year sentence. In an environment that would frighten most people, Boertje-Obed seemed calm, grounded, and philosophical. He was there for a reason, and just fine with it.

As a young man, Boertje-Obed seemed an unlikely candidate for a cell block in Leavenworth Penitentiary. He grew up in a series of Iowa towns – Pella, Sioux Center, Ames. His father was a biology teacher, and the family was deeply religious. For a while, they attended two services at the local Dutch Reformed church every Sunday. Boertje-Obed went to Tulane University in 1973, joined the army Reserve Officers Training Corps to help cover the tuition, and then entered a graduate programme at Louisiana State University to study social psychology. He wrote a master’s thesis on whether personality tests could predict leadership ability and hoped to become an academic researcher. Before that could happen, he became a first lieutenant in the army to fulfil his ROTC obligations.

Assigned to a combat-engineer battalion at Fort Polk, in central Louisiana, Boertje-Obed trained to be a supervisor at a medical-aid station. In battle, his job would be to organize the care of the wounded. In 1980, he was part of a major field exercise in Louisiana. During the war game, a Soviet armoured column headed south from Monroe toward his unit. His battalion camped out in the fields and prepared for a nuclear, biological, or chemical attack, donning gas masks and protective suits. Boertje-Obed was in charge of the medics. He had to make sure that everyone wore the masks for an hour, then two hours, then three, four, five. Members of his unit began to cheat, pulling the masks away from their faces. It was excruciating to wear the masks for ten minutes, let alone four or five hours. The whole exercise seemed pointless to Boertje-Obed; he would die during a real attack.

Boertje-Obed had begun reading about Dorothy Day, who’d encouraged workers at munitions plants to walk away from their jobs. ‘God will lead and provide for you,’ she had assured them. It seemed as though Day were speaking directly to him. He read the Bible and books about civil disobedience. He started to believe you should love your enemies. The field exercise was his tipping point. ‘Nope,’ he thought. ‘I won’t cooperate any more in the planning for nuclear war.’