From Walt Whitman to Siegfried Sassoon

Andrew Motion in 101 Poems Against War writes that poetry reflects our strongest and truest feelings at moments of crisis. Whatever our faith - we compromise, betray or wreck our selves when we take up arms against one another, he says.
Before World War I, the infamous war to end all wars, there was no such thing as a war poet. Yes, there were poets who wrote about war. Walt Whitman in the American Civil War wrote standard glorious lines:

from Ashes of Soldiers

Now sound no note O trumpeters,
Now at the head of my cavalry parading on spirited horses,
With sabres drawn and glistening, and carbines by their thighs,
(ah my brave horsemen!
My handsome tan-faced horsemen! what life, what joy and pride,
With all the perils were yours.)

But it was in 1914-18 that poets became war poets and overturned the scrubbed tables on which the old stuff was dutifully written. No, not written, merely vaingloriously versified. Writing the truth is a nobler art. By World War II the Dulce et Decorum of war was dead and buried as this example of graffiti found in an Army latrine testifies:

Soldiers who wish to be a hero
Are practically zero,
But those who wish to be civilians,
Jesus, they run into the millions.

After the war to end all wars the striking coal miners of the UK were being branded as being worse than the Hun by the ruling class peeling its plovers' eggs and lifting its glasses of mellowed Chateau Rentier. Many of the coal miners demanding a better deal were men who had fought in the rat-infested mud and slime of the Somme trenches on behalf of the Chateau Rentier fraternity with its "Remember Belgium & Enlist Today" "Yes, I mean you young fellow!" and other such propaganda. Yes, those same solid chaps who had got the world into the bloody mess in the first place were now demanding coal to warm their 'members only' billiard rooms. The hypocrisy of it all was mind boggling.
On Sunday 3rd September 1939, as he listened to the declaration of war against Germany, Sassoon was depressed. It all makes me wish that the July 1918 bullet had finished me, he said.

Repression of War Experience

Now light the candles; one; two; there's a moth;
What silly beggars they are to blunder in
And scorch their wings with glory, liquid flame -
No, no, not that,- it's bad to think of war,
When thoughts you've gagged all day come back to scare you;
And it's been proved that soldiers don't go mad
Unless they lose control of ugly thoughts
That drive them out to jabber among the trees.

You're quiet and peaceful, summering safe at home;
You'd never think there was a bloody war on!
O yes, you would...why, you can hear the guns.
Hark! Thud, thud - quite soft - O Christ, I want to go out
And screech at them to stop - I'm going crazy;
I'm going stark, staring made because of the guns.