“The war which is being waged today by the German armed forces under the highest command of Adolf Hitler is a war of an immense reform. It does not only overcome the world of ideas of the French Revolution, but it also exterminates directly all those racially infecting germs of Jewry and its bastards, which now since over a hundred years could develop without check among the European nations. The Jew question, which for 2000 years was a problem for the European nations which was not solved, will now find its solution through the national socialistic revolution for Germany and whole Europe.”

Source: Seven Great Statesmen in the Warfare of Humanity with Unreason (1915), p. 167
Context: The French philosophy of the eighteenth century was in full strength. Those were the years in which Voltaire ruled European opinion, and Turgot could not but take account of his influence. Yet no one could apparently be more unlike those who were especially named as the French philosophers of the eighteenth century. He remained reverential; he was never blasphemous, never blatant; he was careful to avoid giving needless pain or arousing fruitless discussion; and, while the tendency of his whole thinking was evidently removing him from the orthodoxy of the Church, his was a broader and deeper philosophy than that which was then dominant.

Recalling his thoughts of July 1914 on the prospect of war with Germany.
Twenty-five Years (1925)
Context: A great European war under modern conditions would be a catastrophe for which previous wars afforded no precedent. In old days nations could collect only portions of their men and resources at a time and dribble them out by degrees. Under modern conditions whole nations could be mobilized at once and their whole life-blood and resources poured out in a torrent. Instead of a few hundreds of thousands of men meeting each other in war, millions would now meet, and modern weapons would multiply manifold the power of destruction. The financial strain and the expenditure of wealth would be incredible. I thought this must be obvious to everyone else, as it seemed obvious to me; and that, if once it became apparent that we were on the edge, all the Great Powers would call a halt and recoil from the abyss.

An obituary for Adolf Hitler, Aftenposten (7 May 1945)

Der Stürmer, 1944

Pg. 18
Strategy in the Missile Age

Howard Zinn on War (2000), Ch. 21: Just and Unjust War

in Indonesia, Palestine, and Kashmir - has demonstrated convincingly that parties to the most severe conflict may be induced to abandon war as the method of settlement in favour of mediation and conciliation, at a merciful saving of untold lives and acute suffering. Unfortunately, there may yet be some in the world who have not learned that today war can settle nothing, that aggressive force can never be enough, nor will it be tolerated. If this should be so, the pitiless wrath of the organized world must fall upon those who would endanger the peace for selfish ends. For in this advanced day, there is no excuse, no justification, for nations resorting to force except to repel armed attack.
Some Reflections on Peace in Our Time (1950)

"EMU and international conflict", 1997

Report on Peace (8 November 1917) http://marx.org/archive/lenin/works//1917/oct/25-26/26b.htm, Lenin's Collected Works, Vol. 26.
1910s