Ever since, the two parts of Ireland have grown apart but paradoxically today their future is more than ever entwined with the consequence that the age-old Irish Question remains unresolved.
It is one island and two countries although this statement itself rankles many.
Put another way Northern Ireland is part of one country and a great many, probably not enough for now, think it should be part of another country.
This New Year’s message is that after 100 years Northern Ireland needs to seize the moment and boldly determine its own future.
A recent assertion that Northern Ireland should be included directly in the Protocol negotiations was scoffed at by a Co. Antrim born Westminster politician.
But little Northern Ireland should no longer be dismissed as just a bit player, some irrelevant appendage of - any - other country.
The achievements of Northern Ireland and its people outstrip its size and belie the turbulent history. Or perhaps it is that history that has challenged NI and its high achievers.
NI has provided giants in sport and the arts - footballers and actors and musicians both classical and modern - scientists, artists, business leaders and U.S. presidents, and granted, local politicians who achieved global stature.
One shared quality of these giants is a reticence and modesty, illuminating the understated character of the north of Ireland that sets it apart.
Northern Ireland has weathered economic storms, with its backbone of agricultural excellence and an adaptable hard working labour force propelled by a solid education tradition.
A small population, but for a century continually punching above its weight producing giants in every walk of life.
Northern Ireland has earned the possibility to take on the mantle of nationhood in its own right.
This is not to deny either side in the argument over Irish Unity. Indeed, confident and competent governance of Northern Ireland as an independent entity supported by Britain, Ireland and Europe - a Switzerland of the North - may be the only route to finally resolving the Irish Question.
If Irish unity is ever achieved it can only be with two equals - two nation states - coming together voluntarily. Otherwise it will be perceived by a vociferous minority as an annexation on the one hand and a betrayal on the other.
The way forward, as it always has been, is to forget the past and treasure it instead.
There is a movement towards common ground. Unionists are admitting the No Surrender days are over. Nationalist parents say they now recognise they have no more in common with Cork than Chichester and their children proudly say they are Northern Irish because that is special.
Despite the failure of local politicians to act on widespread support for integrated education many of the young are proudly forming common cause by assuming a national Northern Ireland identity regardless of religious or political background.
Je suis NI may be - for now - an exaggeration but your name or your school is no longer defining social circles or career ambitions.
This societal change is about pride in a unique shared heritage - crowned by a peace agreement and a desire for normalised existence within the status quo - and it is sending signals to politicians.
Unionists may bristle about outward signs of Irish culture but it is their heritage, too, and can be seen as contextual to the Orange tradition - both as necessity bestowed with equal protection. The reluctance by the Irish establishment to recognise and celebrate NI’s centenary was unworthy. Unionists should guard against suspension of Stormont as the majority of citizens are seeking local control of local services and Sinn Fein needs to recognise its failure to honour the electorate and negotiate to lift its boycott of sitting as Westminster MPs.
Pretending that Northern Ireland does not exist (or fantasising that it will no longer if the birth rate moves in the right direction) or insisting by the other side that it is treated like a nineteenth century British territory is denying the changing mood of NI citizens.
Politicians from either side simply marking time to achieve some unrealistic emotional or historical ambition let down the bulk of citizens who see the bickering as a distraction that needs to be replaced by their joint priority of economic growth and provision of quality public services.
It is time for our politicians to become statesmen and stateswomen unreservedly representing the whole of Northern Ireland and no other nation.
NI is blessed with many things - an industrious and loyal workforce, a good quality of life for an expanding middle class, a growing diverse population and high standards of behaviour based in part on religious adherence. And, of course, the most distinctive scenery on the island of Ireland.
What has changed is that more people are identifying less with being British or Irish and instead they proclaim being whole-heartedly Northern Irish. They identify with pride to be from a place apart that mainly by its own efforts is casting off the struggles and bitterness of the past.
For Northern Ireland, at the start of 2022, a nation beckons.