As a chaplain in the Vietnam War, he was awarded the Medal of Honor for actions taken on 7 June 1970. He saved more than 20 wounded soldiers after suffering injuries himself. He later quit the priesthood and became a peace activist. In July 1986, as a protest against U.S. policy in Central America, he left his Medal of Honor, along with a letter to President
Ronald Reagan, at the Vietnam Veterans Memorial in Washington, DC.