In all, it was an agreement to disagree (including even over the name of the deal itself), a framework for both sides to amicably coexist, to replace the guns with governing.

It worked, eventually.

But those aspirations are threatened today with renewed sectarianism and the unravelling of key goals in the agreement.

While just 35 pages, the Good Friday Agreement and its creation was anything but hurried. It partly replaced the failed Sunningdale Agreement of the 1970s, built on the Anglo Irish Agreement of the 1980s, the 1993 Downing Street Declaration, and was facilitated by Labour and Tony Blair’s successful election in Britain in 1997.

Nonetheless, numerous problems led up to the Easter period of 1998, including internal fighting among unionists, a fractured republican movement, riots the previous year around Orange Order marches, and tensions with then Northern secretary Mo Mowlam.

But the sense of opportunity was there.

The British and Irish governments, Sinn Féin, the SDLP, and UUP were all aboard the peace train. US peace envoy George Mitchell’s deadline of April 9 focused minds and a deal was hammered out in those iconic and now memorable decaying surroundings of the 1970s-era Castle Buildings, Belfast.

As Blair remarked during the tense talks, the hand of history was upon shoulders.

Fundamentally, the agreement prioritises the “principle of consent” recognising the legitimacy of the aspiration for a united Ireland while also acknowledging the wish of a majority in the North to remain part of the UK. It was inclusive and allowed for a future vote on this, in what now is termed the “border poll” on the province’s status.

A vote can be initiated by the secretary of state if they feel that a majority of people are likely to vote for unification. This vote must not occur more frequently than once every seven years.

The agreement established a number of political institutions. These included the setting up of the 108-member Northern Ireland Assembly and an executive at Stormont, just outside Belfast, allowing elected parties to share power.

The North-South Ministerial Council was also agreed to, facilitating co-operation on both parts of the island. The deal also allowed for the British-Irish Council, involving Scotland and Wales among other devolved administrations.

A key element was the move away from violence. Paramilitary groups, including the IRA, UVF, and UDA, had to hand over their arms to an independent body within two years.

The deal proposed the removal of security installations, a reduction in British army presence, and, crucially, led to the reform of the North’s police force. Prisoners jailed during the Troubles were released and resources provided for their reintegration into society.

Ultimately, full IRA decommissioning was not confirmed by a monitoring body until 2005 while it was 2010 before policing and justice powers were devolved to the North.

While Ireland and the Good Friday Agreement have become an example to the world, influencing peace processes in places such as Colombia, the Korea peninsula, and the Middle East, elements of the pact are outstanding.

These include reconciliation for victims of the Troubles, with an estimated 1,300 murders remaining unsolved from the period. A bill of rights has still to be agreed, contributing to the current impasse over restoring power-sharing.

Indeed, disagreement over same-sex marriage and a recognition of minority languages, including Irish, are central to the stand-off between republicans and unionists at Stormont.

These recent controversies and the subsequent political vacuum in the North’s governing bodies are a reminder of just how fragile the peace process is, particularly with Brexit looming and threatening a hard border.

Sectarianism still thrives, there are more peace walls now than 1998 and sporadic violence and dissident paramilitary acts persist.

Nonetheless, amid fresh attempts to undermine the peace accord by Brexiteers in Westminster, it is worth remembering the ordinary differences the agreement has provided for the North.

Gone are the armed checkpoints, violent street clashes, repeated horrific bombings, bigotry in everyday life, and a fear of entering some neighbourhoods. Lingering problems exist, sure.

Blair’s comments that faithful evening on April 10, 1998, when the Good Friday Agreement was approved, are a reminder of what has changed.

It was and remains the day that peace replaced war, that politics replaced terror, on the island of Ireland.