“The kind of slaughter and violence that we have seen in this war, was in my experience very rare during the Russo-Japanese war. In modern war, the whole people are mobilized. Hence the majority of the troops correspond to the people as a whole. An army in which scandals and atrocities occur in great numbers, must surely reflect a decline in public morality?”

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.

Letter XCV: On the usefulness of basic principles, lines 30-32.
Epistulae Morales ad Lucilium (Moral Letters to Lucilius)
Context: We are mad, not only individually, but nationally. We check manslaughter and isolated murders; but what of war and the much-vaunted crime of slaughtering whole peoples? There are no limits to our greed, none to our cruelty. And as long as such crimes are committed by stealth and by individuals, they are less harmful and less portentous; but cruelties are practised in accordance with acts of senate and popular assembly, and the public is bidden to do that which is forbidden to the individual. Deeds that would be punished by loss of life when committed in secret, are praised by us because uniformed generals have carried them out. Man, naturally the gentlest class of being, is not ashamed to revel in the blood of others, to wage war, and to entrust the waging of war to his sons, when even dumb beasts and wild beasts keep the peace with one another. Against this overmastering and widespread madness philosophy has become a matter of greater effort, and has taken on strength in proportion to the strength which is gained by the opposition forces.

Book 1
De Re Militari (also Epitoma Rei Militaris), Book I, "The Selection and Training of New Levies"

Quoted in "The Military Quotation Book" - Page 15 - by James Charlton - 2002

Writings, The Artful Albanian

"In the Storm" in Le Socialiste http://www.marxists.org/archive/luxemburg/1904/05/01.htm as translated by Mitch Abidor (1 - 8 May 1904)
Context: The Russo-Japanese War now gives to all an awareness that even war and peace in Europe – its destiny – isn’t decided between the four walls of the European concert, but outside it, in the gigantic maelstrom of world and colonial politics.
And its in this that the real meaning of the current war resides for social-democracy, even if we set aside its immediate effect: the collapse of Russian absolutism. This war brings the gaze of the international proletariat back to the great political and economic connectedness of the world, and violently dissipates in our ranks the particularism, the pettiness of ideas that form in any period of political calm.
The war completely rends all the veils which the bourgeois world – this world of economic, political and social fetishism – constantly wraps us in.
The war destroys the appearance which leads us to believe in peaceful social evolution; in the omnipotence and the untouchability of bourgeois legality; in national exclusivism; in the stability of political conditions; in the conscious direction of politics by these “statesmen” or parties; in the significance capable of shaking up the world of the squabbles in bourgeois parliaments; in parliamentarism as the so-called center of social existence.
War unleashes – at the same time as the reactionary forces of the capitalist world – the generating forces of social revolution which ferment in its depths.

Pseudo (1976)