The Western Front: Military Cross
Motivated by patriotism, Sassoon joined the British Army just as the threat of a new European war was recognized, and was in service with the Sussex Yeomanry on 4 August 1914, the day the United Kingdom of Great Britain and Ireland declared war on Germany. He broke his arm badly in a riding accident and was put out of action before even leaving England, spending the spring of 1915 convalescing. (Rupert Brooke, whom Siegfried had briefly met, died in April on the way to Gallipoli.) He was commissioned into the 3rd Battalion (Special Reserve), Royal Welch Fusiliers, as a second lieutenant on 29 May 1915. On 1 November his younger brother Hamo was killed in the Gallipoli Campaign, and in the same month Siegfried was sent to the 1st Battalion in France. There he met Robert Graves, and they became close friends. United by their poetic vocation, they often read and discussed each other's work. Though this did not have much perceptible influence on Graves's poetry, his views on what may be called 'gritty realism' profoundly affected Sassoon's concept of what constituted poetry. He soon became horrified by the realities of war, and the tone of his writing changed completely: where his early poems exhibit a Romantic, dilettantish sweetness, his war poetry moves to an increasingly discordant music, intended to convey the ugly truths of the trenches to an audience hitherto lulled by patriotic propaganda. Details such as rotting corpses, mangled limbs, filth, cowardice and suicide are all trademarks of his work at this time, and this philosophy of 'no truth unfitting' had a significant effect on the movement towards Modernist poetry.
Sassoon's periods of duty on the Western Front were marked by exceptionally brave actions, including the single-handed capture of a German trench in the Hindenburg Line. Armed with grenades, he scattered sixty German soldiers:
He went over with bombs in daylight, under covering fire from a couple of rifles, and scared away the occupants. A pointless feat, since instead of signalling for reinforcements, he sat down in the German trench and began reading a book of poems which he had brought with him. When he went back he did not even report. Colonel Stockwell, then in command, raged at him. The attack on Mametz Wood had been delayed for two hours because British patrols were still reported to be out. "British patrols" were Siegfried and his book of poems. "I'd have got you a D.S.O., if you'd only shown more sense," stormed Stockwell.
Sassoon's bravery was inspiring to the extent that soldiers of his company said that they felt confident only when they were accompanied by him. He often went out on night-raids and bombing patrols and demonstrated ruthless efficiency as a company commander. Deepening depression at the horror and misery the soldiers were forced to endure produced in Sassoon a paradoxically manic courage, and he was nicknamed "Mad Jack" by his men for his near-suicidal exploits. On 27 July 1916 he was awarded the Military Cross; the citation read:
2nd Lt. Siegfried Lorraine [sic] Sassoon, 3rd (attd. 1st) Bn., R. W. Fus.
For conspicuous gallantry during a raid on the enemy's trenches. He remained for 1½ hours under rifle and bomb fire collecting and bringing in our wounded. Owing to his courage and determination all the killed and wounded were brought in.
Robert Graves described Sassoon as engaging in suicidal feats of bravery. Sassoon was also later (unsuccessfully) recommended for the Victoria Cross.
War opposition: Craiglockhart
Despite his decorations and reputation, in 1917 Sassoon decided to make a stand against the conduct of the war. One of the reasons for his violent anti-war feeling was the death of his friend David Cuthbert Thomas, who appears as "Dick Tiltwood" in the Sherston trilogy. Sassoon would spend years trying to overcome his grief.
At the end of a spell of convalescent leave, Sassoon declined to return to duty; instead, encouraged by pacifist friends such as Bertrand Russell and Lady Ottoline Morrell, he sent a letter to his commanding officer entitled Finished with the War: A Soldier’s Declaration. Forwarded to the press and read out in the House of Commons by a sympathetic member of parliament, the letter was seen by some as treasonous ("I am making this statement as an act of wilful defiance of military authority") or at best as condemning the war government's motives ("I believe that the war upon which I entered as a war of defence and liberation has now become a war of aggression and conquest"). Rather than court-martial Sassoon, the Under-Secretary of State for War, Ian Macpherson, decided that he was unfit for service and had him sent to Craiglockhart War Hospital near Edinburgh, where he was officially treated for neurasthenia ("shell shock").
Before declining to return to active service Sassoon had thrown the ribbon of his Military Cross into the river Mersey. According to his description of this incident in Memoirs of an Infantry Officer he did not, as one would infer from the context of his action, do this as a symbolic rejection of militaristic values, but simply out of the need to perform some destructive act in catharsis of the black mood which was afflicting him; one of his pre-war sporting trophies, had he had one to hand, would have served his purpose equally well.
The novel Regeneration, by Pat Barker, is a fictionalised account of this period in Sassoon's life, and was made into a film starring James Wilby as Sassoon and Jonathan Pryce as W. H. R. Rivers, the psychiatrist responsible for Sassoon's treatment. Rivers became a kind of surrogate father to the troubled young man, and his sudden death in 1922 was a major blow to Sassoon.
At Craiglockhart, Sassoon met Wilfred Owen, a fellow poet who would eventually exceed him in fame. It was thanks to Sassoon that Owen persevered in his ambition to write better poetry. A manuscript copy of Owen's Anthem for Doomed Youth containing Sassoon's handwritten amendments survives as testimony to the extent of his influence and is currently on display at London's Imperial War Museum. Sassoon became to Owen "Keats and Christ and Elijah"; surviving documents demonstrate clearly the depth of Owen's love and admiration for him. Both men returned to active service in France, but Owen was killed in 1918. Sassoon, despite all this, was promoted to lieutenant, and having spent some time out of danger in Palestine, eventually returned to the Front. On 13 July 1918, Sassoon was almost immediately wounded again—by friendly fire when he was shot in the head by a fellow British soldier who had mistaken him for a German near Arras, France. As a result, he spent the remainder of the war in Britain. By this time he had been promoted acting captain. He relinquished his commission on health grounds on 12 March 1919, but was allowed to retain the rank of captain. After the war, Sassoon was instrumental in bringing Owen's work to the attention of a wider audience. Their friendship is the subject of Stephen MacDonald's play, Not About Heroes.