The calendar says that it happened less than eight years ago, but the calendar feels wrong. It feels as if it occurred in another era altogether.

Less than eight years ago, on Sept. 17, 2007, a group of Blackwater contract security guards passing through Baghdad's Nisour Square went on a wild shooting spree, using heavy machine guns and rocket-propelled grenades to kill or wound more than 30 Iraqi civilians who happened to be in the square at the time. Nobody has ever proved what initiated the barrage -- some of the guards claimed that their convoy had come under attack, and they may have honestly perceived that to be the case. Other witnesses, including other Blackwater guards, testified that it was unprovoked.

However, those whom they had killed or wounded, including two dead children, had been unarmed. American investigators later found no evidence that an ambush had occurred in the square and no evidence that the convoy had come under fire. Instead, they found that the Blackwater guards had treated the crowded square as a free-fire zone, acting with utter disregard for the lives of others.

Yesterday, four of those Blackwater guards were sentenced in a federal court in Washington. One man was sentenced to life in prison; three others were sentenced to serve 30 years. Such sentences are probably appropriate, but as I read accounts of the courtroom proceedings, I couldn't help but compare their fates to those of the low-ranking American prison guards at Abu Ghraib. Those young soldiers at Abu Ghraib probably deserved prison sentences as well for badly mistreating Iraqi prisoners, but it is just as true that they served as convenient scapegoats.  Their superiors involved in the much larger, more inhumane and officially sanctioned program of organized torture carried out in the name of the United States have never been called to account, and never will.

Likewise, the shootout at Nisour Square was our invasion of Iraq writ small. Like the invasion, it began with claims of danger that later proved totally exaggerated if not outright lies. American firepower was used indiscriminately, to shock and awe a population that we were ostensibly there to help yet ended up harming. In the end, we did more damage than good. More specifically, the outrage that followed the Nisour Square shooting, and the Iraqi resentment at feeling helpless in their own country at the hands of invaders, ended up hardening Iraqi sentiment against the United States and making it impossible for President Bush to negotiate an agreement that would have allowed U.S. forces to remain active in Iraq while being exempt from Iraqi law.

And while those four Blackwater guards will serve long, long sentences for their cowboy behavior, those who pushed us into the larger invasion of Iraq are still in Washington, still in positions of influence in politics, the media and think tanks, and astonishingly still arguing for a do-over in taking on neighboring Iran, on the premise that this time we'll get it right.

Like I said, Nisour Square was less than eight years ago. Can we have forgotten so much in so short a time?