Siegfried Loraine Sassoon was born on September 8^th, 1886, at a house named Weirleigh in the village of Matfield, Kent. His parents were Alfred Sassoon, who belonged to a notable family of Jewish merchant traders, and Theresa Thornycroft, a member of an equally notable family of artists and sculptors. Sassoon was the second of the couple’s three sons.

Alfred Sassoon, who had been cut off by his family for marrying outside the faith, left Theresa when the children were still small, and died not long afterwards. The keenly-felt loss of his father was to be a major influence on Siegfried’s development and later actions. Although his poetic ambitions appeared in childhood, Siegfried’s somewhat isolated upbringing (he did not go to school until he was fourteen) and easy circumstances (for despite being excluded from the Sassoon fortune, he had a private income which ensured he did not need to work) combined to turn him into a lackadaisical young man, by his own admission.

Having dropped out of his degree course at Clare College, Cambridge, and lived for a time in London while vainly attempting to carve himself a literary career, Sassoon managed one minor commercial success with The Daffodil Murderer, a parody of John Masefield. Some of his other verse was privately published, without acclaim, and then came the First World War. Sassoon joined up on the day before war was declared, and went into the Sussex Yeomanry as a mere trooper, in the hope of being able to keep his horse. He saw no action for ?over a year. It was only when, after being incapacitated in a fall, he determined to start afresh with a commission in the Royal Welch Fusiliers, that his military career really began.

During his time at the Western Front, Sassoon became friendly with two men who were formative influences on his life. One was the younger poet, Robert Graves, who encouraged Siegfried to look with new eyes on his surroundings. The other was David Thomas, who was tragically killed in 1916. This death, combined with the loss of his brother Hamo in a naval action, caused Sassoon great emotional turmoil. A sympathetic picture of his suffering is drawn by Graves in Goodbye to All That. While recovering from ?trench fever at a convalescent hospital in Oxford, Siegfried became friendly with Lady Ottoline Morrell and her circle, including intellectuals and pacifists such as Bertrand Russell. Russell is credited by some with having been the catalyst leading to the issue of the Soldier’s Declaration, which was sent to the papers and read out in the House of Commons in May, 1917. Sassoon, in the grip of a "neurosis", had by now thrown his medals in the River Mersey and refused to report for duty. His glittering military record ensured that the authorities declined to court-martial him. Instead, he was sent for treatment to Craiglockhart Military Hospital in Edinburgh.

Craiglockhart was an experimental facility, whose remaining buildings are now part of Napier University. The attentions of the psychiatrists who worked there were reserved for officers, of whom Siegfried Sassoon was one and Wilfred Owen another. Owen was several years younger than Sassoon, but had read a recent collection of poetry, The Old Huntsman, in which Siegfried had begun to give an effective voice to the bitterness and pain of the war experiences he shared with so many others. As a result, Owen hero-worshipped Sassoon, and they quickly became fast friends. Both were soon released from Craiglockhart, Sassoon after several months under the care of the kindly Dr William Rivers, whom he came to see as a surrogate father. Sassoon was posted to Palestine, but Owen did not return to active service until the following year.