I had almost forgotten what a shit Yeats could be. I don't mean his flirtation with Italian fascism, which Conor Cruise O'Brien first publicised; after all, Churchill was a bit enamoured of the younger Mussolini. And Yeats remains one of my favourite poets. No, what I am recalling – thanks to a wonderful book just published in Dublin – is his outrageous decision to expel the poetry of Wilfred Owen from the 1936 Oxford Book of Modern Verse.

"Passive suffering is not a theme for poetry," the great man intoned. And in a later letter, Yeats wrote: "When I omitted Owen, whom I consider unworthy of the poet's corner of a country newspaper, I did not know I was excluding a revered sandwich-board of the revolution ... He is all blood, dirt and sucked sugar-stick ... There is every excuse for him, but none for those who like him."

I am taken aghast by this arrogance. For here is Yeats, safe in his Irish retreat, spitting out the mud of the trenches in which up to 35,000 Irish soldiers died between 1914 and 1918, pissing on the young man who was shot by a sniper on the Ancre and who gave us the poetry which Benjamin Britten so memorably used in his magnificent War Requiem.

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Even when confronted by the death in action of his own friend – Major Robert Gregory, accidentally shot down by Italian guns in 1918 – Yeats's poem, the incredible "An Irish Airman Foresees His Death", manages to avoid Gregory's pro-British patriotism and imply that parochial loyalties ("My country is Kiltartan Cross/My countrymen Kiltartan's poor") led him to his death.

Our War: Ireland and the Great War, edited by John Horne and published by the Royal Irish Academy and RTE, the Irish state radio and television service, is the latest historical attempt to face up to those tens of thousands of young Irishmen who were fighting on the Western Front when a few hundred of their countrymen were rising up against the British in Dublin in 1916. Those long-dead soldiers were in the wrong uniform in the wrong war, fighting for the wrong country. Or so it was supposed when the survivors came home to a nation which was demanding independence and freedom from the forces of the crown.

In a series of essays, the authors of Our War – originally Thomas Davis lectures (an excellent Irish equivalent of the Reith lectures in Britain) – show just how much the Great War affected Ireland. Even in 1924, after independence, 70,000 Irish men and women were in the streets of Dublin for Remembrance Sunday and those who were deprived of British pensions paid, literally, for their former patriotism to the King.

When Nurse Emily Harris wrote to him from Kingstown (now Dun Laoghaire in County Dublin) in 1926 – "it was Your Majesty's loyal subject's delight and privilege as a daughter of the British Empire during the late Great War to serve as an officer in Your Majesty's Army'' – and pleaded for help in her post-war poverty, Downing Street briskly sent her letter on to the Taoiseach's department in Dublin. "I should be glad if, in any reply sent to Miss Harris, it may be made clear that her letter was, by His Majesty's command, referred to the Government of the Irish Free State," it stated. When Margaret Freeman wrote from Phibsboro in Dublin, appealing to the Irish government for a pension for her 1914-18 ex-soldier husband, she received a tart reply from the Taoiseach's office. "I am to ... state that the question of an award of pension in respect of service in the World War of 1914-1918 would not be a matter for the Government of Ireland." Nurse Harris, by the way, was forced to sell all her possessions – "and your loyal subject's heart is broken" – to survive.

Unlike the Brits, Irishmen came home to a country that was at war. Stones were thrown at them in the streets. Military medals were hidden away. The Lutyens war memorial was allowed to decay, overgrown and ignored until recent years. The 16th and 36th Divisions returned from the blood of the Somme, the first to be forgotten in post-war Dublin, the second to be remembered for ever as Protestant Ulster's sacrifice for Britain.

Conscription was never attempted in Ireland and the massive loss of Irish life was one of the principal reasons Eamon de Valera ensured that the Irish Free State, as it was then called, remained neutral through the Second World War. Having written my PhD thesis on Irish neutrality, I have to say that I think Dev was right. Ireland might have suffered another civil war, although the propaganda which the British used against Dublin at this time has stuck like old mud on a new shoe.

I was brought up on tales of German U-boats skulking around Irish ports to receive fuel from anti-British villagers. But I spent three months visiting every village on the Irish west coast and researching the Irish Coastwatching service archives and I can attest that no U-boat – ever – put in to an Irish port. Just one man in Kerry told me that as a child, he gave food to a U-boat crew in Brandon Creek; and a story that a U-boat captain surfaced off Dingle town with a shipwrecked Greek crew because he knew the mayor of Dingle was also false. I know this because when I first wrote about the incident, the elderly Kriegsmarine submariner actually sent me a letter to say that he had rescued the crew (of a ship called the Diamantes) but never knew the mayor of Dingle.

Of course, by the Second World War, Ireland was isolated, watching the shadows on the wall of Plato's cave, receiving the decaying corpses from the Battle of the Atlantic, trying to forget the greatest blood sacrifice of 1916 – on the Somme rather than in Dublin. Our War will go a long way to recall the tide of Irish blood that drifted ashore at Gallipoli and broke the hearts of more than just Nurse Harris. Every Englishman and woman should read it.