Dorothy Day, along with
Peter Maurin was one of the founders of the
Catholic Workers movement. She was a
socialist, a
pacifist, an
activist, and is
currently under consideration for
beatification by the Roman Catholic Church. She was a long-time correspondant of
Thomas Merton.
Even during times of war Dorothy Day and her newspaper The Catholic Worker took a pacifist stance, which made her very unpopular, especially during "good" wars like World War II. J. Edgar Hoover had her name placed on the list of people to be "placed in custodial detention" (jail) in the event of a national emergency.
Her justification for her pacifism was based on something called the "just war doctrine" and there were many articles published in her newspaper discussing it and pacifism in general.
In 1965 Dorothy Day was asked to write a clear, theoretical, logical pacifist manifesto. She responded:
"I can write no other than this: unless we use the weapons of the spirit, denying ourselves and taking up our cross and following Jesus, dying with Him and rising with Him, men will go on fighting, and often from the highest motives, believing that they are fighting defensive wars for justice and in self-defense against present or future aggression."
You can read more about Dorothy Day at the Casa Juan Diego (a Catholic Worker house of hospitality) website, http://www.cjd.org