The news from Iraq that Islamic terrorists have now taken over cities that American troops liberated during the Iraq war must have left an especially bitter after-taste to Americans who lost a loved one who died taking one of those cities, or to a survivor who came back without an arm or leg, or with other traumas to body or mind.
Surely we need to learn something from a tragedy of this magnitude.
Some say that we should never have gone into Iraq in the first place. Others say we should never have pulled our troops out when we did, leaving behind a weak and irresponsible government in charge.
At a minimum, Iraq should put an end to the notion of "nation-building," especially nation-building on the cheap, and to the glib and heady talk of "national greatness" interventionists who were prepared to put other people's lives on the line from the safety of their editorial offices.
Those who are ready to blame President George W. Bush for everything bad that has happened since he left office should at least acknowledge that he was a patriotic American president who did what he did for the good of the country - an assumption that we can no longer safely make about the current occupant of the White House.
If President Bush's gamble that we could create a thriving democracy in the Middle East - one of the least likely places for a democracy to thrive - had paid off, it could have been the beginning of a world-changing benefit to this generation and to generations yet unborn.
A thriving free society in the Muslim world, and the values and example that such a society could represent, might undermine the whole hate-filled world terrorist movement that is seeking to turn back civilization to a darker world of centuries past.
But creating such a society, if it is possible at all, cannot be done on the cheap, with politicians constantly calling for us to announce to the world - including our enemies - when we are going to leave. The very idea is silly, but everything silly in not funny.
We haven't yet announced when we are going to pull our troops out of Germany or Japan, and World War II was over more than 60 years ago. Turning those militaristic countries around was one of the great achievements in human history. Their neighboring countries have been able to enjoy a peace and security that they had not known for generations.
Perhaps what was achieved in Germany and Japan made it seem that we might achieve something similar in Iraq. But "the greatest generation" that had fought and survived the horrors of war around the world was under no illusion that trying to turn our defeated enemies around would be easy, quick and cheap.
Creating democracy in Germany and Japan was a goal, but not a fetish. Creating a stable and viable government amid the ruins and rubble of war was the first priority and a major responsibility. You cannot create instant democracy like you are making instant coffee.
There are prerequisites for a free society, and the foundations of democracy cannot be built on chaotic conditions with widespread uncertainty and fear. To hold elections for the sake of holding elections is to abdicate responsibility for the sake of appearances.
The biggest danger is that you will create a government that will work at cross purposes to everything you are trying to achieve -- a government you cannot rein in, much less repudiate, without destroying your own credibility as representatives of democracy. That has happened in both Iraq and Afghanistan.
By contrast, in both Germany and Japan power was turned over to elected officials at such times and in such degree as conditions seemed to indicate. Eventually, both countries resumed their roles as sovereign nations. But we didn't publish a timetable.
Today, with terrorists threatening to at least fragment Iraq, if not take it over, it is a sobering thought that Barack Obama and his key advisers have a track record of having been wrong about Iraq and other foreign policy issues for years, going back before they took office - and no track record of learning from their mistakes.