What is the greatest single performance in the Irish theatre in the last 25 years? A silly question, perhaps. But if I had to answer it, I would say it was Donal McCann playing Thomas Dunne in Sebastian Barry’s tragedy The Steward of Christendom at the Gate Theatre in Dublin in 1995.

And I would not be alone in that: McCann’s infinitely poignant embodiment of an old man in an asylum, haunted by the memory of his dead son, was one of those events that leave a permanent mark on the minds of most of those who encounter it.

But here, a quarter of a century on, is the twist: McCann’s character, Thomas Dunne, was the last chief superintendent of the Dublin Metropolitan Police (DMP) before it was merged into An Garda Síochána.

In 1995, his performance in Barry’s astonishingly beautiful play seemed like a kind of exorcism. Dunne, though imaginatively transformed, was a real man, and in fact Barry’s own great-grandfather.

It seems that there is still very much a hierarchy of victims when we come to deal with the legacy of the earlier Troubles The drama was so powerful because it seemed in part to be laying a ghost to rest. Irish audiences were able, it seemed, to come to terms with the human reality of an Irish Catholic policeman who served the Crown, lost his son in the first World War, and fell into the abyss of amnesia to which those who find themselves on the wrong side of history are consigned.

Yet now those ghosts are back to haunt us. Barry’s Thomas Dunne laments that “soon there’ll be nowhere in Ireland where such hearts may rest”.

The Government clearly hoped that the now-postponed ceremony at Dublin Castle next Friday, remembering those who served in the DMP and the Royal Irish Constabulary (RIC) might allow these anomalous figures to rest peacefully at last in the official memory of the Irish revolution. Instead, the gesture seems to have raised those spectres from their unquiet graves.

The mayors of Dublin, Cork, Galway, Waterford and County Clare have joined Fianna Fáil and Sinn Féin in rejecting the event. Dublin city councillors even voted overwhelmingly to call it “obscene”.

Hierarchy of victims It seems useless for the Government to insist, as it has done repeatedly, that the event was meant to be a commemoration, not a celebration, or that most of the 549 members of the RIC and the 14 members of the DMP who were killed between Easter Monday 1916 and the disbandment of the RIC in August 1922 were mainstream members of Irish Catholic society.

In 1919, when the War of Independence got under way, the typical RIC constable was 35 years old and had been serving for 15 years. He had, in other words, joined up at the age of 20 in 1904. That was a different world. The cataclysm of the first World War was a full decade away.

The vast majority of Irish nationalists sought Home Rule within both the United Kingdom and the Empire. Republican militants were a noisy but marginal fringe group.

Even revolutionaries such as Desmond FitzGerald saw no prospect of armed rebellion: “Those of us who thought of Home Rule as something utterly inadequate were a very small minority, without influence, impotent. If we had been more critical of ourselves, we should have been reduced to utter disheartenment.”

RIC members came to feel abandoned by the London government The young men who joined the DMP and RIC from small farms and rural villages can hardly be blamed for being no better at predicting the future. They were thinking of their own futures, of how to escape the confines of small holdings and get secure and pensionable work without having to emigrate.

Having a policeman in the family was not much different to having a priest. Of Kerry, for example, it was said that “you could hardly go into a house without a son in the police, or if they didn’t they had a brother.” These sons and brothers had no idea that they were signing up for a civil war.

The first person to die in the Easter Rising of 1916, Constable James O’Brien, from Kilfergus, Co Limerick, wasn’t even armed. He was standing at the entrance to the upper yard of Dublin Castle when he was shot in the head by the Abbey actor Sean Connolly. O’Brien thought that the rebels were simply parading.

Of Constable Michael Lahiff who was killed by the rebels at St Stephen’s Green shortly afterwards, Constance Markievicz told Nora Connolly that she “could not shoot when it came to the point as she recognised him and had known him before”.

Such innocence and such intimacy are of course precisely the things that are obliterated in violent conflict. The RIC’s lack of preparation for war and close proximity to the local population made it extremely vulnerable to attack. Its members came to feel abandoned by the London government.

Violent repression In the maelstrom of violence, the ordinary policemen could not escape the taint of brutality. They were unquestionably part of a system of violent repression. The thuggery of the Auxiliaries and the Black and Tans made the very notion of ordinary policing impossible.

Even the DMP became deeply implicated: its political “G division” tortured suspected Republicans in Dublin Castle.

By the end of 1921, complexity, nuance and a sense of human tragedy had become thoroughly redundant.

There is decency in the way the policemen who died in 1916 are now remembered alongside the other victims in Glasnevin Cemetery But complexity was still mere reality – the reality of many Irish families. The writer Seán Ó Faoláin, for example, was the son of an RIC man in Cork city, but he himself became an IRA man. “Men like my father”, he remembered in his autobiography in 1963, “were dragged out, in those years, and shot down as traitors to their country. Shot for cruel necessity – so be it. Shot to inspire necessary terror – so be it. But they were not traitors. They had their loyalties and they stuck to them.”

Is it obscene merely to remember such men? Must there be a hierarchy of victims in which they remain, not just at the bottom but even lower down, in the underground darkness of oblivion?

We have, supposedly, been trying to rise above such mentalities, to accept that history, when it turns violent, sweeps all sorts of human lives into the gutter. A society that has moved beyond violence does not leave them there.

We have been evolving, as a decent polity must, a sense of tragedy, of the way people get trapped by forces they cannot control or even fully comprehend.

There is decency in the way the policemen who died in 1916 are now remembered alongside the other victims in Glasnevin Cemetery or the way the names of the two RIC men shot dead in the Soloheadbeg ambush, Constables James McDonnell and Patrick O’Connell, are now recorded at the monument on the site.