“Let’s not have any more wars to end all war.”

Source: Kafka on the Shore (2002)

A remark to his private secretary, Lord Sandon, in May 1919. From Terence H. O'Brien, Milner, Viscount Milner of St James and Cape Town 1954-1925, 1979, Constable, p. 335.

Statement, sometimes dated to have been made in 1916, as quoted in Reading, Writing and Remembering : A Literary Record (1932) by Edward Verrall Lucas, p. 296
Undated

A Prescription for Hope (1985)
Context: The hope of a benevolent civilization was shattered in the blood-soaked trenches of the First World War. The "war to end all wars" claimed sixteen million lives, and left embers which kindled an even more catastrophic conflagration.
Over the sorry course of 5,000 years of endless conflicts, some limits had been set on human savagery. Moral safeguards proscribed killing unarmed civilians and health workers, poisoning drinking waters, spreading infection among children and the disabled, and burning defenseless cities. But the Second World War introduced total war, unprincipled in method, unlimited in violence, and indiscriminate in victims. The ovens of Auschwitz and the atomic incineration of Hiroshima and Nagasaki inscribed a still darker chapter in the chronicle of human brutality. The prolonged agony which left 50 million dead did not provide an enduring basis for an armistice to barbarism. On the contrary, arsenals soon burgeoned with genocidal weapons equivalent to many thousands of World War II's.
The advent of the nuclear age posed an unprecedented question: not whether war would exact yet more lives but whether war would preclude human existence altogether.

Source: Goliath

Source: Watchmen

Lyrics, Solo

As quoted in "Edward Teller Is Dead at 95; Fierce Architect of H-Bomb" http://www.nytimes.com/2003/09/10/obituaries/edward-teller-is-dead-at-95-fierce-architect-of-hbomb.html, New York Times (Sept. 10, 2003) by Walter Sullivan.

1961, UN speech
Context: Mankind must put an end to war — or war will put an end to mankind.
So let us here resolve that Dag Hammarskjold did not live, or die, in vain. Let us call a truce to terror. Let us invoke the blessings of peace. And as we build an international capacity to keep peace, let us join in dismantling the national capacity to wage war.
Context: We meet in an hour of grief and challenge. Dag Hammarskjold is dead. But the United Nations lives. His tragedy is deep in our hearts, but the task for which he died is at the top of our agenda. A noble servant of peace is gone. But the quest for peace lies before us.
The problem is not the death of one man — the problem is the life of this organization. It will either grow to meet the challenges of our age, or it will be gone with the wind, without influence, without force, without respect. Were we to let it die, to enfeeble its vigor, to cripple its powers, we would condemn our future. For in the development of this organization rests the only true alternative to war — and war appeals no longer as a rational alternative. Unconditional war can no longer lead to unconditional victory. It can no longer serve to settle disputes. It can no longer concern the great powers alone. For a nuclear disaster, spread by wind and water and fear, could well engulf the great and the small, the rich and the poor, the committed and the uncommitted alike. Mankind must put an end to war — or war will put an end to mankind.
So let us here resolve that Dag Hammarskjold did not live, or die, in vain. Let us call a truce to terror. Let us invoke the blessings of peace. And as we build an international capacity to keep peace, let us join in dismantling the national capacity to wage war.