During World War II, when he became a conscientious objector who nonetheless served with an ambulance unit with Allied forces through North Africa, Italy, France and Germany:

Murphy was with the British troops who liberated Bergen-Belsen, the Nazi concentration camp where Anne Frank died. “When they first went in, there were something like 10,000 dead bodies all over the ground. Starved dead bodies. Then there were these numerous sheds. The victims inside were as close together as the fingers on your hand, the dead and the dying. It was a horrible, horrible thing.”

After the war he spent 20 years in the spiritually-based Shiloh Community (a group founded by Eugene Crosby Monroe and originally located in western New York), baking bread and pruning trees.

In the 1980s he made three trips to Nicaragua, which reminded him of what he had experienced in Europe during the Second World War, as he said during the 1986 fast:

I worked with survivors of the Nazi atrocities after the army unit I was with liberated Belsen … The Jews, Gypsies and other prisoners there told me the same kinds of stories I’ve heard from survivors of Contra atrocities during my trips to Nicaragua. For over 40 years, I have done everything I possibly could to prevent the horrors of the Holocaust from recurring.

For the rest of his life he worked for peace, including participating in protests at the School of the Americas at Fort Benning, Georgia.

Aside from a couple of notable actions that thrust him momentarily into the public eye, Duncan lived a quiet life, even as his tree-trimming helped keep him active and fit.

Keeping his needs simple and living a largely nomadic life for the last few decades, Duncan engaged in the work of conscience in a world writhing with violence and injustice: spending oneself freely to sound the alarm and to offer an example of what every one of us can do, if we are willing.