These are some of the quotes that Peace Pilgrim (a woman who went on a 28-year pilgrimage for peace, walking across North America) used to carry in the pockets of her tunic:
General Omar Bradley: "Wars can be prevented just as surely as they can be provoked, and we who fail to prevent them must share in the guilt for the dead."
General Douglas MacArthur: "I have known war as few men now living know it. Its very destructiveness on both friend and foe has rendered it useless as a means of settling international disputes."
Dwight D. Eisenhower: "Every gun that is made, every warship launched, every rocket fired, signifies in the final sense a theft from those who are hungry and are not fed, those who are cold and not clothed." Speaking "as one who has witnessed the horror and lingering sadness of war - as one who knows that another war could utterly destroy this civilization," he warned against the military-industrial complex.
John F. Kennedy: "Mankind must put an end to war, or war will put an end to mankind... War will exist until that distant day when the conscientious objector enjoys the same reputation and prestige that the warrior does today."
Pope John Paul II: "In the face of the man-made calamity that every war is, one must affirm and reaffirm, again and again, that the waging of war is not inevitable or unchangeable. Humanity is not destined to self-destruction. Clashes of ideologies, aspirations and needs can and must be settled and resolved by means other than war and violence."
(from the book
Peace Pilgrim: Her Life and Work in Her Own Words, Chapter 9, "Extensions of Pacifism")
more at
http://peacepilgrim.net/book/chapt9.htm