'Although forty-seven with a wife and seven children, Montague volunteered to join the British Army. Grey since his early twenties, Montague died his hair in an attempt to persuade the army to take him. On 23rd December, 1914, the Royal Fusiliers accepted him and he joined the Sportsman's Battalion.'
He was a 'journalist; author of a number of acclaimed books; 24th Battalion Royal Fusiliers, 1914; full sergeant (grenadier-sergeant), 1915; lieutenant; captain (intelligence); press-officer; after the war one of the authors in the 20's that wrote devastatingly of WWI. Disenchantment was his rather philosophical book about World War I combat.'Here's a detailed summary and analysis of Disenchantment, according to which, 'The book is ... difficult to read, full of allusions to events, perhaps well-known then but now obscure, packed full also of references to Thucydides, Shakespeare and other allusions of a classic liberal education.'
From Montague's diary (Dec., 1917):
To take part in war cannot, I think, be squared with Christianity. So far the Quakers are right. But I am more sure of my duty of trying to win the war than I am that Christ was right in every part of all that he said, though no one has ever said so much that was right as he did. Therefore I will try, as far as my part goes, to win the war, not pretending meanwhile that I am obeying Christ, and after the war I will try harder than I did before to obey him in all the things in which I am sure he was right. Meanwhile may God give me credit for not seeking to be deceived. (Quoted from the above-linked Spartacus bio.)Several of Montague's works are available on-line.