Most wars are doomed when they invade the lives of the public and the public starts saying "no more".
Well today Afghanistan will invade our lives once again.
Not just the lives of a bereaved wife, mother or father. But the lives of all of us.
The moment will come when six coffins containing the bodies of the soldiers killed in the worst single attack on British troops in this conflict will return home.
Such repatriations have happened before of course.
They've happened time after time. So many times, in fact, that the emotional ceremonies were in danger of becoming what they most certainly were not routine.
But this time it will be different.
It will be different because, if the polls are to be believed, there's been quite a significant shift in public mood.
When the fallen used to come back, there was sadness and tears and grief, but also a feeling that it is the inevitable consequence of war.
And this was coupled with the belief that this was the right war.
The war to rid Afghanistan of al Qaeda, to track down the mastermind of 9/11 Osama Bin Laden and to put a new government in place.
Well that's all happened. But the still the war goes on.
And now fewer and fewer people appear to understand why. Even military top brass admit we can't win the war in any recognised military sense.
At least not without putting troops into Pakistan. And even then it's unlikely. In fact it would only make things worse.
So people ask "why"? And when the bodies still come home, the sadness is tinged with a growing unease.
The war invaded our lives in another way last week.
It was when the American soldier went beserk, slaughtering 16 men, women and children as they lay sleeping in their beds.
We know these things happen in war and perhaps we shut our minds to it when the war is perceived to be 'worth it'.
But when the cry is already "What on earth are we doing there?" then such atrocities stamp on our sensitivities, tear at our tolerance and make the call for an exit ever louder.
Politically too things are going awry.
President Karzai, corrupt and weak, is making great play of telling Nato to keep its troops out of Afghan villages and in their bases.
It is very difficult to fight a war on that basis. And this war can only be fought with the consent of the Afghan government and people.
And then there's the Taliban deciding to withdraw from any talks about peace talks with the Americans.
David Cameron and Barack Obama are speaking bravely about "real progress" and "finishing the mission".
They speak of preparing the Afghan army to take over. And in a way they are right to do so.
As the Defence Secretary told me after the deaths of the six troops, to quit early or speed up the withdrawal would, perhaps, give the appearance of cutting and running.
It is neither man's war but Mr Obama and Mr Cameron know it may become so if it ends badly.
And there's no greater challenge to politicians overseeing a conflict than a growing cry of "why"?