While a famous song by an equally famous Irish group has given generations of people an idea of the conflict on the island, the famous 'Troubles' that raged between Catholic Republicans and Protestant Unionist Loyalists from the 1960s to the late 1990s and beyond, it cannot replace a visit in person to understand how fragile this peace in Northern Ireland, even 20 years later, still seems.
There are of course the optimists, who are not really worried about the consequences of Brexit on the famous Good Friday Agreement. Among them, Desmond McCain, a middle-aged man met at random during a visit to one of the memorials dedicated to 12 Northern Irish workers who were forced one day in January 1976 to get off their buses and were executed coldly.
Desmond knew these workers. "We know who did this", says this man who now lives in England and had not returned to Northern Ireland for 40 years. Who did this? For him, no doubt, it's the IRA, the Irish Republican Army.
For this man, Brexit is good news. "We are going to leave this overly bureaucratic EU and as soon as possible will be the best". This will be beneficial both economically and politically, he believes. "Today's young people are very different from our time; it is no longer possible to have a war; just look at the recent Irish referendum on abortion, it would not have been possible 40 years ago", he wants to believe.
But in the heart of Belfast, in the offices of the European Commission which manages peacekeeping projects, projects called Peace or Interreg programmes to support cross-border cooperation, the daily work shows that things are not so simple.
Here, there is not much concern about the continuation of projects and programmes after Brexit, after March 2019. But we realize on a daily basis that sparks can quickly return, especially among disadvantaged, early school leavers or socially marginalized youth. Young people who may be attracted to 'paramilitary' criminal groups and acts potentially directed against the other community.
Since 1995, the EU has in any case spent €2.2 billion on Peace projects, both in reconciliation projects at the beginning and more recently in supporting disadvantaged young people and raising awareness of past stereotypes and hostile attitudes.
European programmes also help veterans of this war and their wives or families.
As a reminder, this conflict has left more than 3,500 people dead and thousands wounded. For officials working on these programmes, violence remains at a low level today, but the level of civil disobedience is high. In addition, Northern Irish society remains divided, if not segregated.
"People refuse to pass through this or that neighbourhood so as not to cross paths with the other community", explains one of these officials. Education also remains a fragmented sector with relatively few mixed schools involving both communities.
And there also remain in the heart of Belfast these Walls of Peace, the "Peace walls", covered with paintings and artistic graffiti over several hundred meters. They were built in 1969 by the British government to separate communities and protect them from clashes. In 2003, the Northern Irish government committed itself to destroying them within ten years.
However, by 2018, it seems that there is no longer any desire to see it disappear. Beyond a piece of history and an artistic work, "these walls always make people feel safer", explains an Irish diplomat.
Some of these walls also still have doors that allow people to pass through during the day and, still in 2018, these doors continue to close every evening as soon as night falls. (Original version in French by Solenn Paulic)