"What I want to ask, in all simplicity, is this - whether, in face of the tremendous conflict which is now raging, whether, in view of the fact that apart from every other consideration, the Irish people, North as well as South, are upon the side of the allies and against the German pretension today, is it not possible from this war to make a new start; whether it is not possible on your side, and on ours as well, to let the dead past bury its dead, and to commence a brighter and a newer and a friendlier era between the countries?"

Thus spoke William Redmond MP in March 1917 during his last speech to the House of Commons before departing for the Western Front. His heartfelt words moved the Commons deeply.

None of the members listening to him on that last parliamentary day of his life could possibly have imagined that the war which had consumed so many lives, and was to consume so many more, including that of the impassioned speaker before them, far from constituting a new start for reconciliation in Ireland was to provide merely fresh, and often vigorously exploited, opportunities for misunderstanding, hatred and murder.

Willie Redmond's unit, the Royal Irish Regiment, was serving near Ypres with the 16th Irish Division. That division was largely drawn from the pre-war Irish National Volunteers; and the division alongside it was the 36th Ulster Division, drawn from the pre-war Ulster Volunteer Force. To the surprise of outsiders, the two divisions got on exceedingly well, though it was of course no surprise to their members.

Aside from the Irishness they held in common - and unionist identity in 1917 was still an emphatically Irish quality - their morale was high. Both divisions had fought in fierce battles in 1916, with 16th Division casualties (nearly 2,700 dead) actually higher than those of the 36th (nearly 2,000).

They were distinctly different from the other British army divisions. An English officer with the Connaught Rangers, Rowland Feilding, said of his men that they would do nothing if ordered; if asked, they would do anything. "I can never express in writing what I feel about [them]," he said in a letter home. "Freezing or snowing, or drenching rain; always smothered with mud; you may ask any one of them, any moment of night or day, `Are you cold?' or `Are you wet?"' and you will always get but one answer. The Irishman will reply - always with a smile - `Not too cold, sir,' or `Not too wet, sir'."

He was as much impressed by his Irish officers, cheery, friendly, open towards outsiders, and his trench mortar officer, a former barrister on the midland circuit, James Patrick Roche, born in Kerry, but then resident in Monasterevin, he regarded as the wittiest raconteur he had had ever met, as well as being a superb soldier: "As brigade mortar officer, a genius."

Whenever Roche was about to utter one of his quips, a small grin would settle on his face, lingering afterwards when the jest was complete.

Perhaps the finest soldier in the 36th Ulster Division alongside the 16th was Henry Gallaugher who, during the fighting on the Somme the previous summer, had personally killed six snipers, later collecting 28 injured men from no-man's-land.

His letters home to Manorcunningham were farmer's letters and spoke not so much of war but of the fields of Donegal and the prospects for the coming flax harvest.

That spring of 1917, the two Irish divisions were put through intensive training for the coming assault on the German-held Flanders villages of Messines and Wijshaete beneath which sappers had burrowed miles of tunnels to plant a score of huge mines beneath enemy trenches.

They played football together, and officers visited one another's messes, sometimes discussing their political differences, and by all accounts ending their conversations in the best of humour. They were confident young men, rightly proud of their military prowess and their identity.

That morning of June 7th, 1917, the men of the two divisions prepared to go over the top. Some of the Dublin Fusiliers said a decade of the Rosary for the Germans they were sure were doing to die in the coming minutes. At 3.10 a.m., while the nightingales were still singing in Rossignol Wood, nearly a million pounds of high explosive detonated beneath the enemy positions, obliterating numerous strong points, and causing one of the largest man-made explosion so far in history.

Simultaneously, British artillery opened fire on German positions, and the two Irish divisions rose from the trenches and advanced over the ground still quaking from the detonations, through the falling debris, which killed many of them.

Surviving German artillery and the redoubtable German machine-gunners opened up on the advancing soldiers, and in their separate engagements Redmond and Gallaugher were hit, the latter's arm being shattered. Both insisted on continuing. "This'll do me rightly," declared Gallaugher as he threw away his useless rifle and continued his advance. Both were hit again. Redmond was brought back to his lines by stretcher-bearers from the 36th Ulster Division, under the command of a Lieut Paul, from Howth. Both Gallaugher and Redmond died of their wounds. Paul himself was to die shortly afterwards.

Casualties were, by the deplorable standards of that time, remarkably light, but a single shell had fallen into a group of Irish officers. Lieut Col Feilding came across their corpses and lifted the sandbag covering a face. "It was discoloured by the explosion of the shell that had killed him, but otherwise was quite untouched, and it wore the same slight smile that in life used to precede and follow his wonderful sallies."

Capt James Patrick Roche MC, aged 29, son of Stephen and Elsie Roche, of Monasterevin, brilliant wit and a gallant soldier, was dead.

Both divisions suffered cruel losses, but their spirits were high. They had participated in a stunning victory; they could not know that ahead of them, side by side yet again, lay the pure Calvary of Third Ypres, where they were - in common with so many British divisions - to be squandered in one of the most appalling campaigns of history.

But in a way even more grievous was to be their place in mythology; the Ulsters were already on their way to immortality within the unionist population of Ireland, but the 16th Irish Division, composed overwhelmingly of Irish nationalists and whose casualties had exceeded those of the Ulsters by the time it was disbanded in 1918, was destined for four score years of neglect and amnesia. Indeed, many of its members were to be murdered at home simply because they had served in the British army.

Flanders was where together the two divisions were victorious together; Flanders, two months later, was where, in the smothering and bitter swamplands of Frezenberg Ridge, they were united in defeat; Flanders is where, next Wednesday, some 80 years after the end of the war which consumed so many Irish volunteers of all political colours, their common sacrifice will be commemorated jointly by the heads of state of Britain and Ireland; and Flanders is where Willie Redmond's farewell words to the Commons seem finally to be coming true.