In my judgment, to depict the soldier's life as intolerable horror is a propagandist attempt to intimidate the soldier's son. Another and more serious blot upon recent fiction is the attempt to blacken the soldier. To say that war does, and must, develop all the animal in man and leave other qualities undeveloped is a libel on the dead and the living. Could the golden record of 50 000 Irishmen dedicated that day speak with tongues, the war novel of 1929 would hide its head for shame. Men would say that their comrades fought a clean fight and fell honourably dead in honour's cause. War fiction would be soon forgotten, but war facts would speak to generations yet unborn.(Irish Times, Nov. 11, 1929, p. 4)No authors or novels are named in the report, but Robert Graves' Goodbye to All That was published in 1929, as was Richard Aldington's Death of a Hero. Outside the UK, both Hemingway's Farewell to Arms and Remarque's All Quiet on the Western Front appeared in 1929.
The claim that the novels overstated the physical horrors of the War reminds me of Wittgenstein's offhand remark to the effect that the War wasn't really as bad as people thought it was. (I can't locate a source that gives Wittgenstein's exact words.)
Update (Feb. 23): Shortly after Luce's death, there appeared in the Irish Times an item called 'Some Recollections of Arthur Luce'. (July 2, 1977, p. 13) The author, identified only by the initials T. C. K. M., attended some of Luce's classes before WWI and maintained an acquaintance with Luce throughout his long life. T. C. K. M. observes that when Luce returned to Dublin from the battle front for a week-long leave in 1916, it was apparent that 'the shock to all his cherished ideals was shattering'. The author does not elaborate on these ideals but had earlier characterized Luce as a conservative Victorian 'and a believer in the Empire'.
Based on this description, one would expect Luce to have shared (or at least been sympathetic to) the bitter disenchantment of Graves and the other novelists and poets whose youthful patriotism had been shattered by the War. However, T. C. K. M. says that after returning to the front, Luce suffered from shell-shock, which was followed by 'a period of over-tension, withdrawal, a hardening of his ideas and a tendency to push them to a logical but impractical extreme'. Again, T. C. K. M. does not say which ideas hardened, but the implication seems to be that Luce doubled down on his old, conservative ideals.
So, on the one hand, some veterans (like Graves) were led by their war experiences to abandon in disgust their earlier, more patriotic ideals while, on the other hand, some veterans (like Luce) became even more committed to those ideals. I wonder if, in addition to the consciously followed reasons for their ideals, veterans in this second group were influenced by a psychological tendency to cling more fervently to beliefs for which they felt they had paid a price. More generally, the more one has invested in something, the more reluctant one is to abandon it; and this remains the case when the 'something' consists of ideals and the 'investment' involves risking one's life.