Sassoon, pictured in 1916, was commended for acts of bravery
A campaign to save the papers of World War I poet Siegfried Sassoon for the nation has been bolstered by a grant of £550,000.
The National Heritage Memorial Fund's award to Cambridge University puts it closer to raising the £1.25m needed to permanently secure the collection.
It includes a manuscript of Sassoon's statement refusing to return to duty after being wounded.
The poet, whose work captured the futility of war, died in 1967.
The Cambridge University campaign to purchase Sassoon's papers from his family is led by his official biographer Max Egremont.
The grant will leave the fund with £110,000 still to raise.
Mr Egremont said: "If the rest of the money can be raised, the papers will soon be available to the public.
"The response to the appeal has been heartening in these difficult times and shows Sassoon's popularity and importance as a writer."
SASSOON: SOLDIER AND POET
Studied law at Clare College, Cambridge but dropped out in 1907 without a degree
Lived the life of a country gentlemen before joining the military when war broke out
Joined the 3rd Battalion Royal Welch Fusiliers as second lieutenant and sent to France in 1915
Awarded Military Cross in 1916 and nicknamed "Mad Jack" by his platoon despite becoming increasingly depressed by the horror of war
Declined to return to duty in 1917, following a period of convalescent leave in England
"It is particularly appropriate that they will be in Cambridge, Siegfried Sassoon's old university and a place that he loved."
Sassoon's archive includes pocket notebooks written on the Western Front, love letters to his wife Hester, poetry books, photographs and letters from other writers.
Organisers of the Cambridge University Library's campaign say the archive, when added to existing holdings, would create the most significant collection of Sassoon manuscripts anywhere.
The campaign, launched in June, has been backed by author Sebastian Faulks, the former Poet Laureate Sir Andrew Motion and military historian Richard Holmes.
Author Michael Morpurgo, who included extracts of A Soldier's Declaration in his novel Private Peaceful, said his words echo down through the ages so powerfully because they are still sadly so relevant.
He said: "Every generation, all of us, should read, mark, and never forget how it was, how it really is for young men when older men send them off to war. We may then learn."