Before the week was out, Mr Ashdown's warning was borne out in particularly grisly fashion, with the massacre of 14 Serb farmers, which bore an uncanny tit-for-tat resemblance to the murders of Kosovo Albanian farmers at the start of this year which, more than anything, steeled Nato's resolve for war.
Tragic though these killings were, and while the administration of Bernard Kouchner (who got the job Mr Ashdown wanted) seems to have been slow to get to grips with the situation, if we take stock of the Kosovo conflict just 53 days after it ended, we must conclude that it has turned out far better than anyone could have hoped.
What is most extraordinary is that by the end of last week, the UN High Commission for Refugees reported that 720,000 refugees had returned to Kosovo, which must be nearly all of them. Given the widespread assumption that refugees never return, or at best that they would be forced to spend the Balkan winter in tents, this rapid reversal of such a huge movement of people represents a stunning vindication of Nato's campaign. Even the small numbers of refugees taken into this country begin to return today.
Against this background, what is surprising is that there have not been more atrocities committed by the returning Albanians. In the towns and cities of Kosovo, most of the Serb minority appear to have stayed and continue to live in the same apartment blocks as their Albanian neighbours. The rural areas were always going to be more difficult to police.
And, of course, just because the restoration of Kosovo has gone relatively smoothly so far does not mean that the situation cannot quickly turn ugly. As Mr Ashdown warned, "criminality and political intimidation are moving fast" into the vacuum left by the departed Serb military. Britain should do all it can - in days, not weeks - to help Mr Kouchner build a credible police force and legal system. And, although Slobodan Milosevic's tank- revving (the modern equivalent of sabre-rattling) of yesterday can safely be ignored, the threat posed by Serbian resentment over the long term, both in Kosovo and in Serbia, cannot.
It was never going to be easy for outsiders to run a province so riven by historic hatreds, and it was never going to be easy to organise the return of the best part of a million people. But so far the achievement on both fronts has been heroic, and we should pay tribute to all concerned.