It is nearly 90 years since Michael Collins was killed — and yet only now has it been possible for a Fianna Failer to address the annual rally at Beal na mBlath in west Cork.

It requires a political memory that cherishes the open wound, and reaches for the sandpaper and salt at any sign of healing, to have made such a rift so enduring. That young Fine Gael boycotted the rally because of the minister's presence suggests that they should rename themselves Ogre Fine Gael.

There's almost nothing one can consciously do about a party-political culture, and the memories it cherishes.

It exists with its own ethos with its own gods in its own timeframe; and outsiders such as myself may rant and rail at the “deficiencies” of a particular culture, but that will make no difference. Adherents adhere. That's what they do, regardless of criticism.

So, Brian Lenihan did a good job in the circumstances, with the usual knee-bend in the direction of mythic truth that lies at the heart of the Collins legend.

“Here was a man at constant risk of arrest and death running a ruthless guerrilla war and masterminding the highly efficient intelligence system which ensured its success.” Well, if it was so successful, why the Civil War?

Now our history is unlike any others, and I'm just telling you this as a simple truth: if you venerate Michael Collins, you must also venerate his methods, and central to these is the killing of unarmed men in front of their wives. Moreover, for all the minister's remarks about Collins's “success”, the cause for which Collins introduced this policy — a united Irish Republic — is as far away today as it was when Collins's boys padded through Dublin streets, to shoot sleepy men in their pyjamas.

And though his memorialists annually applaud Collins's acumen as Minister for Finance, the actual methods that he most enduringly bequeathed to Ireland were about bloodshed, not banking.

Last week, as the Beal na mBlath organisers were preparing for Lenihan's visit, a group of Protestants from south Armagh met members of the Northern Historical Enquiries Team investigating the mass murder of 10 Protestant workmen in 1976. What happened there is perhaps the worst single atrocity of the Troubles, not because of the numbers involved — Birmingham, Bloody Sunday, La Mon and Dublin/Monaghan claimed more lives — but because of the diabolical methodology involved.

Consider this: ten Protestant men were lined up against their bus and then shot down in a point-blank fusillade. And then, each man was finished off, with a single headshot, with a different weapon and a different gunman for each victim. Ten men were killed, and 10 men did the shooting, in a synchronised coup de grace. In other words, this was not merely a sectarian atrocity, it was also a choreographed blooding exercise for 10 young IRA men of south Armagh, in all, firing 136 rounds into their victims. With their final 10 headshots, in a single murderous moment, they each signed a contract in human blood that would bind them in perpetuity to the IRA.

Moreover, these 10 killings are ballistically linked with 35 other murders, and more than 100 further terrorist incidents, before the penumbra of death spreads too wide for measurement.

The Kingsmill massacre was the defining act of the south Armagh brigade of the Provisional IRA.

Henceforth, its authority over the area was total.

What foul and now forgotten deeds were subsequently done by the 10 young vampires who had been formally inducted into the brotherhood of bloodshed that terrible day?

Weeks before Collins was killed, and not far away from Beal na mBlath, a roughly comparable cull (though without the elaborate synchrony) of Protestants had been conducted by IRA men in the Bandon Valley. It is one of the massive achievements of both Irish historiography and of popular memory that these killings in May 1922 should have been so totally eradicated.

But why else was Collins in west Cork, but to attempt to curtail such atrocities? When I first wrote about these sectarian killings in the late 1980s, many people were indignant — why, such events had never happened. Oh, but they did, and not merely in Cork, but also in south Armagh at around the same time.

The men of six Protestant families were taken out and shot by an IRA unit that was led a man who was later to have a barracks named after him in Dundalk town — Frank Aitken.

And comparable events could only have happened again in 1976 because we had not learnt our history; and, therefore, we could not possibly learn from it.

It is not possible to control political violence in an island divided such as ours. You cannot clinically kill without consequence rolling through the communities. You cannot take life without murder sooner or later becoming a depraved norm — either in the Bandon Valley in 1922, or Kingsmill in 1976, or Wherever in 2012.

To deplore the political divisions that have endured in the Republic since independence, yet to exult in the events that gave rise to those divisions is as grotesque as a still-grieving widow enthusiastically applauding the unveiling of a statue to her husband's killer.