Peter De Mott was born in 1947 and died in 2009. He served in the Vietnam War as a United States Marine and later served in Turkey as a U. S. Army translator. During this time he developed strong anti-war beliefs, and joined the Catholic Worker Movement in 1979, with a focus on addressing the causes of poverty, unemployment and homelessness. In the early 1980s he spent time living at Jonah House and participated in the Plowshares Movement.
He married Ellen Grady (sister of Clare and Teresa) in 1984, and they had four daughters together.
He died when he fell out of a tree that he was trimming. He is interred in Greensprings Natural Cemetery in Newfield, New York.
On March 17, 2003, Peter, Danny Burns, and Clare and Teresa Grady poured their blood at the local Army/Marine recruiting center, two days before "shock and awe" bombing of Iraq began, in an act of nonviolent symbolic action. They became known as the Saint Patrick's Day Four. In 2003, he traveled with Danny Burns to Iraq as part of a Christian Peacemaker Team.