September 28, 1912, was Ulster Day: 417,414 people (the men signing a Covenant and the women an accompanying Declaration), under the guidance of the Unionist Party, pledged their opposition to Irish Home Rule:
"Being convinced in our consciences that Home Rule would be disastrous to the material well-being of Ulster, as well as of the whole of Ireland, subversive of our civil and religious freedom, destructive of our citizenship, and perilous to the unity of the Empire, we, whose names are underwritten ... do hereby pledge ourselves in solemn Covenant ... to stand by one another in defending for ourselves and our children, our cherished position of equal citizenship in the United Kingdom, and in using all means which may be found necessary to defeat the present conspiracy to set up a Home Rule Parliament in Ireland."
The Times remarked of Ulster Day that "the impression left on the mind of every competent observer is that of a community absolutely united in its resistance to the act of separation with which it is threatened."
Rudyard Kipling, in his poem Ulster 1912, went further:
What answer from the North?
One Law, One Land, One Throne,
If England drive us forth,
We shall not fall alone.
Well, here we are, a century later, and six of the Ulster counties remain in the United Kingdom. Bearing in mind that the vast bulk of the pro-Union majority lived within those counties, it's not unreasonable to argue that unionists have cause for a full-throated celebration next month.
There isn't a united Ireland and it seems pretty unlikely that there will be one any time soon. Indeed, a recent Belfast Telegraph/LucidTalk opinion poll indicated that support for Irish unity is continuing to diminish within Northern Ireland, while most of the evidence south of the border suggests that there is no particular demand to upset the constitutional status quo.
That's a crucially important development. For decades, it was taken for granted that unionism was for Protestants, while nationalism was for Catholics.
It was this view which fashioned and directed Ulster unionism from the 1880s onward (the time of the first Home Rule Crisis) and which dominated the thinking of Unionist governments in Northern Ireland from 1921 to the mid-1960s.
Put bluntly, most unionists regarded most Catholics as Irish nationalists and, in regarding them as so, didn't put any pressure on their governments to reach out and win them over.
There is no doubt that Catholics in Northern Ireland generally regarded themselves as second-class citizens: not because they necessarily were nationalists, but because they were Catholics and assumed to be nationalists - and therefore an internal enemy of the state. The Civil Rights movement didn't fight for equality for nationalists per se, but for equality for Catholics.
Meanwhile, the IRA tried to capitalise on the 'sectarian' problem and, in so doing, proved itself to be equally sectarian: for it, too, took the view that all Catholics were anti-Union, as well as anti-unionist.
Yet it now looks like an Assembly and political structures which allow Catholics/republicans/nationalists to have a full role has resulted in increasing numbers of Catholics finding themselves in the pro-Union (rather than unionist) camp.
Again, that's good news for unionists. The percentage of Catholics has increased significantly since 1921, yet the overall number supporting Irish unity has fallen.
Peter Robinson has tapped into this reality and is presenting the DUP as a more tolerant, inclusive and embracing face of unionism.
Yes, the DUP remains as opposed to republicanism as ever it was, yet it now makes a very clear distinction between political belief and religious background. Putting it at its simplest level, the DUP no longer scares, or spooks, most Catholics. So, 100 years on, the dream of a united Ireland looks further away than ever. The IRA and Sinn Fein have bought into an internal settlement, with Northern Ireland securely anchored to the UK. The Dail is content to underwrite a partitionist settlement.
Sectarianism hasn't disappeared (a charge that runs both ways), but it isn't the fixed point of politics here anymore.
Ironically, it is the UUP, the remnant of the party led by Carson and Craig a century ago, which looks like the biggest loser.
From being the dominant political force in unionism and in Northern Ireland, it is now vying with Alliance for fifth place in the polls and is the only one of the five which isn't represented in the House of Commons.
So nearly eclipsed has it been by the DUP that it is actually hosting a joint Covenant celebration dinner with them on September 28: an event which will allow the DUP to take possession of one of the UUP's last remaining assets - its legacy.
The unionism of 1912 is as strong, determined and confident as it ever was. It didn't get all that it wanted, but it got much more than its opponents imagined it would get. Ireland has changed and so, too, has the relationship between London and Dublin and between Belfast and Dublin.
It may no longer be the dominant political force here, but it looks like the tide of history will continue to flow in its favour.