Constable Ronan Kerr was only 12 when a Real IRA car bomb ripped through the centre of Omagh in August 1998. While he was readying himself for a new school year at the end of that summer, the world's media descended upon the town.
There was widespread global revulsion over the massacre, which claimed the lives of adults and children from Spain, England and Ireland.
Tony Blair and Bertie Ahern - the double-act who had successfully secured the Good Friday Agreement just a few months earlier - vowed to hunt down those responsible for the biggest atrocity of the Troubles.
Meanwhile, those behind a six-month bombing and mortar campaign designed to thwart the chances of a political settlement in Northern Ireland initially went into a blind panic.
One Real IRA leader - a former Provisional killer - drank himself into a stupor the evening of the explosion. Meanwhile, the Real IRA's founder, Michael McKevitt, became the target of international news organisations and the ire of ordinary citizens.
Locals in Dundalk did the once-unthinkable and marched on the McKevitt-Sands' home in nearby Blackrock to protest about the slaughter in Omagh.
Eventually, McKevitt tried to negotiate a way out by offering a ceasefire. It seemed in those days and weeks after the carnage that Omagh may have been the biggest atrocity of the Troubles, but it was surely going to be the last.
Yet here we are, 13 years later, with republican dissidents returning to Omagh. Once more they have been the subject of national and international opprobrium, with Gerry Adams labelling those responsible "murderers" and Martin McGuinness branding them traitors to their own community.
None of this denunciation, however, is going to convince any of the three republican dissident organisations to halt their violence. Because, when the deluge of condemnation subsides, one crystal-clear, brutal piece of logic remains intact: that we're only doing now what you did before.
The Real IRA, Continuity IRA and Oglaigh na hEireann (ONH) may not have popular support, but they have this critical part of republican logic on their side.
They can point to the fact that, for instance, up until 1994, the Provisionals conducted the same strategy the dissidents so cruelly deployed in Highfield Close when they killed Constable Kerr.
From the start of the Troubles, the Provisionals specifically targeted Catholic RUC officers and recruits to the newly-formed Ulster Defence Regiment (UDR).
The Provisionals did not just target Catholic members of the security forces because they regarded them as 'traitors'. They also needed the police and UDR to be seen as exclusively Protestant and unionist in their portrayal of their armed campaign as a war of liberation against imperialist oppressors.
As well having this twisted historical logic on their side, dissident republicans are benefiting - paradoxically - from the normalisation of security policy on both sides of the border.
Over the last decade, post-Omagh bomb, resources on the anti-terrorist front have been run down significantly. There has, for instance, been a dramatic decrease in the number of Special Branch officers in strategically important Garda Siochana stations along the border.
Although the gardai have scored some important successes against the dissidents, intelligence on the three anti-ceasefire groups remains patchy. In Northern Ireland, the PSNI's grip on intelligence matters regarding the three main republican organisations is even weaker.
If the dissidents can maintain their current level of violence (following a lull of several months), this might have to force a rethink regarding security policy both in Northern Ireland and the Irish Republic. One success the security forces and politicians can at least point to is the fact that, in spite of years of targeting, the Real IRA, CIRA and ONH campaigns have not deterred young Catholics from joining the PSNI.
So much so that the PSNI announced late last month that they were abandoning the policy of positive discrimination known as the '50:50' rule.
The police service is now more representative of the community than ever before in the history of Northern Ireland.
The majority of nationalists, like their unionist neighbours, will, of course, be appalled over this latest outrage to be visited upon Omagh.
However, back in the 1970s and 1980s, a lack of popular legitimacy did not put off those driving the republican armed campaign against the British presence when that violence was condemned by successive taoisigh and even by a pope visiting Ireland.
None of this deterred the Provisionals - nor will it deter the dissidents.