The book was compiled with the full co-operation of Priestley's family
Letters by writer JB Priestley from the trenches of World War I have been published for the first time.
They present a different view of the playwright's war experiences compared to his morale-boosting BBC broadcasts during World War II.
In the letters he wrote of the "horrors of war" and said he had returned home with "a chip on my shoulder - probably some friend's thigh bone".
The letters have been published to mark the 90th anniversary of Armistice Day.
In the early years of World War II , Priestley's radio broadcasts immediately followed Winston Churchill's addresses to the nation.
His early writing career was interrupted by the outbreak of World War I, which saw him enlist in the army at the age of 20, where he saw active service in France.
'Strange and familiar'
In one letter home, Priestley said: "I've seen some terrible sights and endured some hardships but, believe me, I never lost my nerve and, strange to say, I felt a strange exaltation of the soul at the expense of the body.
"Do not be afraid for me. I am not afraid. I suppose I am a man now.
"I am certainly going through an ordeal. Perhaps it would be as well if everybody went through some test of manhood."
The book, Priestley's War, was compiled by author Neil Hanson with the full co-operation of Priestley's family.
His son Tom remembers listening to his father's broadcasts in World War I.
"I was at boarding school and I was allowed down in my dressing gown as a special favour and would sit listening to this strange but very familiar voice coming out of the radio," he said.
I am certainly going through an ordeal. Perhaps it would be as well if everybody went through some test of manhood
Priestley was eventually taken off air after he began calling for Britain to become a country "fit for heroes" when the troops returned.
That message infuriated Churchill and the broadcasts were abruptly dropped.
Priestley, who died in 1984 aged 89, went on to become a co-founder of the Campaign for Nuclear Disarmament.
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