The protracted unionist war against David Trimble - waged by opponents both inside and outside his party - is over for the time being. This is the key fact of contemporary Ulster politics.

On at least three occasions since the Belfast Agreement, Mr Trimble's unionist opponents have sensed victory - at the beginning of the last week of the referendum campaign where the polls spoke of a collapse of Protestant support for the agreement; when the first votes of the forum election were being counted and it looked as though Mr Trimble would not have enough loyal supporters returned to elect him First Minister; and, finally, when the Daily Telegraph poll on the day before November's crucial Ulster Unionist Council vote which gave the go-ahead for devolution predicted a narrow defeat for the party leadership.

Mr Trimble could, of course, re-ignite this war and lose it, if he attempts to walk away from the pledges given then - pledges which were absolutely necessary to secure a narrow victory. Is he likely to do so, given that his present position assures not only his personal dominance but, more importantly, the dominance of a political position within unionism which seeks a historic compromise on reasonable and realistic terms?

The position of the British government is crucial here. In March, Tony Blair told the Scotsman that decommissioning must take place, because "people have got to know if they are sitting down [in the Executive] with people who have given up violence for good".

There is every reason to believe that the private position here is exactly the same. There is also good reason to believe that the British government does not believe that Mr Trimble could persuade the UUC - even in the unlikely event that he was of a mind to do it - that republicans could stay in government sans decommissioning.

The implication of the post-dated resignation strategy adopted by Mr Trimble in November - only ad opted with the greatest understandable reluctance and very late in the day - is well understood: Mr Trimble simply had to do it if he was to survive. There is one thing worse than the agreement suffering a serious setback in February and that is losing Mr Trimble, without whom the project of the agreement cannot be revived.

So, Mr Trimble's unionist opponents have plenty to think about this Christmas. Thus far, to put it bluntly, they have got it wrong.

This is not a reference to their failure to predict the outcome correctly on those occasions when Mr Trimble has first squeezed by with a few votes to spare. Anybody can get that sort of thing wrong. It is a far deeper problem of failure of analysis. They misunderstood the strategy of the British and Irish governments, which was always going to give a pro-agreement unionism a credible story to tell.

On the British side, this necessity was firmly grasped throughout the 1990s; even - or perhaps especially - officials relatively unpopular with unionists like Sir Quentin Thomas, whose retirement from government is announced, understood that a settlement could not be advanced by pushing the unionist leadership's back to the wall.

While senior Irish officials were in general agreement on the broad principle, not all were happy to pay the full price - an ambiguous change to Articles 2 and 3 - demanded. Hence the long delay between John Major's "Corfu test" set for Albert Reynolds in 1994 and the satisfactory Ahern-Trimble talks on this issue in London in November 1997, which led directly to the Heads of Agreement of January 1998; a breakthrough probably made easier by the fact of significant changes of negotiating personnel on the Irish side.

David Trimble's story was always going to consist of certain core elements: the restoration of a Stormont assembly, a unionist First Minister, practical cross-Border co-operation responsible to that assembly, an east-west dimension, the removal of the irredentist Articles 2 and 3.

The price was in a sense politically acceptable but emotionally high: Sinn Fein respectabilised and forgiven in government, even though republicans had not asked for forgiveness for their part in 60 per cent of the total volume of violent death during the Troubles.

However, his unionist opponents always insisted that in purely legal constitutional terms, Mr Trimble had got it wrong, that these arrangements were inherently transitional to Irish unity. Yet most unionists chose to back Mr Trimble on this point despite the insistent disagreement of one of Northern Ireland's foremost legal-political minds, Robert McCartney.

The real criticism of Mr Trimble lies elsewhere. Did his narrow legal focus on the constitutional "correctness" of the arrangements lead him to concede too much ground in other critical areas? Was he also perhaps too lulled by reassurances like the Prime Minister's pre-referendum pledge: "I give this specific reassurance . . . no local policing" - so that the Patten proposals on policing came as a genuine surprise?

Where does this leave anti-agreement unionists? For some time, the DUP has been astute enough to avoid the pure logical rejectionism of Mr McCartney. It has drawn the lesson from the South African experience that conservative forces can not allow themselves to opt out of the process. Indeed, it had gone for an each-way bet: at one moment, Peter Robinson, as a responsible minister, happily drops the sour face mode to engage with Derry nationalists and republicans, on the other hand, they continue to denounce the agreement.

It is a position which infuriates the Ulster Unionists. In fact, it is perfectly sustainable until the February denouement, but then whatever happens - barring a Trimble political suicide note - the DUP will have to change. Either in government or outside it - pursuing the argument on decommissioning - it will be increasingly impossible for the DUP to present Mr Trimble as the arch-betrayer.

These matters are not just of importance for unionism but for the whole island. There has as yet been little sign of an influx of middle-class talent into the UUP; for the foreseeable future, we are going to have to make do with the quantum of unionist political talent as it now is. The outcome of the D'Hondt distribution of ministries demonstrates a still considerable unionist capacity to punch below one's weight, in part due to the legacy of unionist disunity.

Over time, though, DUP ministers, if the experiment survives, will be naturally drawn away from the "end of the world is nigh" rhetoric to a more pragmatic and consistent assertion of the joys of devolution.

The British State may be consistently pro-consent in its ideology - this is quite compatible with a minimalist intellectual approach which is decidedly not pro-British in any instinctive sense.

It cannot however be expected to improve the unionists' game for them, however alarmed it is by signs of political incompetence which threatens the desired outcome of turning off the Northern Irish troubles and turning the province into another placid, prosperous euro-religion - "of whose ministers nobody has even heard", as one official has put it.

Some of the wiser heards in the Department of Foreign Affairs envisage an essentially "steady state" approach to cross-Border co-operation for the next five years or so. This is helpful, but the Irish Government can not be expected to reward unionism for not improving its performance. The worry is that the good governance of Northern Ireland depends to a very considerable degree on the capacity for reflection of Mr Trimble's unionist opponents.

Despite his attack on Rousseau in his Nobel speech in Oslo, Mr Trimble has followed Rousseau's most celebrated dictum here: he has forced them to be free. Freed of their shackles - essentially a commitment to a settlement on terms which were never acceptable to nationalists - what will they make of it?

Paul Bew is a Burns Library Visiting Professor at Boston College