For those who relish the "what if" school of hypothetical history, it is interesting to recall that if al Qa'eda had delayed a month or two before launching the 9/11 attacks, Donald Rumsfeld would probably not have been around to mess up America's military and diplomatic response. This intriguing detail emerges in the recently published biography of Mr Rumsfeld by Bradley Graham, a veteran Washington Post reporter. By September 2001, Mr Rumsfeld was making such a hash of reorganising the Pentagon, while succeeding only in antagonising the more talented generals, that George W Bush was reluctantly gearing up to fire his friend after less than a year in the post.
Then the planes slammed into the Twin Towers, and another one into the Pentagon. Mr Rumsfeld rushed on impulse from his office and briefly helped rescuers to pull his staff from the rubble before he was summoned back to his desk to brief the president about what was to be done. Obviously you cannot sack a defence secretary when America is under attack, so Mr Rumsfeld survived, flourished briefly, then crashed and burned, and the rest is real history, and a really awful outcome.
Mr Rumsfeld's impulsive intervention to help save his staff seemed at the time to encapsulate the can-do, united spirit of an America numbed by the realisation it was at war with a dangerous, ephemeral enemy. In the current rancorous mood Washington has sunk into, it is easy to forget what America was like in the weeks after the towers were brought down. Back in the autumn of 2001, partisan politics were suspended, and Democrats learned to conceal their disdain for Mr Bush, Mr Rumsfeld, Karl Rove and the rest of the Republican White House inner circle. Foreign leaders who regarded Mr Bush as a third-rate Texan cowboy rushed to offer their very public support. Even the French managed to keep their historic loathing of Americans under control.
The courage of the firemen digging out Ground Zero inspired thousands of young Americans to volunteer for military service. Back then, they positively hankered after a mission to Afghanistan to do Uncle Sam's work in eliminating the Taliban, and hunting down Osama bin Laden. It seemed so simple and clear-cut in those days, such an uncontroversial war to join. Who would have thought, back then, that the war in Afghanistan would go on longer than the Second World War, and that Washington's failure to come up with a sensible and humane way of incarcerating foreign combatants would leave America's diplomatic reputation in shreds?
As the nation rallied to the president's colours in the "war on terror", perhaps it was pure hubris that blinded Mr Bush and Mr Rumsfeld to this problem, combined, one cannot help thinking, with a fair measure of anti-Muslim sentiment. It is difficult to imagine Americans treating Europeans like that, or - given the sensitivities of their racial past - Africans. From the moment the first combatants were captured, Mr Rumsfeld was adamant that these loosely defined "foreign fighters" should be afforded no rights under the Geneva Conventions, and indeed, that they must not be referred to as prisoners.
This became a genuine challenge for the men and women charged with putting this into effect. Brigadier General Michael Lehnert. a 25-year veteran of the US Marine Corps, was put in charge of building a prison at Guantanamo Bay at the end of 2001. Deeply patriotic and an observant Roman Catholic, Brig Gen Lehnert decided that if the prisoners were to have no formal protection under the Geneva Conventions, he would nevertheless run a regime "guided" by them. He was appalled by the way the prisoners were handed over into his custody.
The Pentagon had insisted that the 40 heavily armed guards who accompanied the first batch of 20 detainees from Afghanistan wore full body armour. A photographer caught the famous image of these wretched prisoners, chained and with their eyes covered to ensure maximum sensory disorientation, and clad in the now infamous orange jump suits, stained by their own urine and faeces. That picture set in train the public relations and diplomatic catastrophe that was, entirely predictably, to follow.
For his part, Brig Gen Lehnert did what he could to make amends: he was exceptionally tough on the military guards he found to have abused the detainees; he appointed a Muslim to serve as a prison chaplain. Copies of the Quran were ordered in bulk, and prayers were announced through loudspeakers five times a day. Reports of this "laxness" got back to Washington and an enraged Mr Rumsfeld - far from applauding his initiative and humanity - ensured Brig Gen Lehnert's term was not extended, and he left the installation after only 100 days.
With Brig Gen Lehnert gone, the Pentagon could transform the camp into a place out of sight and mind, and where brutal interrogation - actually far too long after the event to be useful to investigators - could proceed without restraint. Incredibly, these failures were repeated in Iraq after the 2003 invasion, when Mr Rumsfeld was adamant that the US needed only 130,000 troops, and no proper thought was given to rebuilding infrastructure, or what was to be done with the thousands of Saddam Hussein's hardline supporters who had run the country.
What happened in Abu Ghraib was in many respects worse than at Guantanamo's Camp Delta, not least because the deliberately inadequate and confusing rules about prisoner treatment left junior military personnel in an ethical and legal vacuum. Some of them tried to do good; some blew the whistle on the more egregious behaviour of their comrades. But too often, perfectly decent young American men and women, in the de-humanising world of that prison, were robbed of their moral judgement and acted in bestial terms.
This much we know, but what is galvanising Washington this week is the way the Obama administration seems to be shifting from its previous position of ruling out prosecutions of CIA interrogators who had exceeded humane bounds. In truth, Mr Obama may in many ways be just an observer of a good old-fashioned Washington turf war between the veteran Democratic operator and new CIA director Leon Panetta, and the attorney general, Eric Holder.
Attorney generals are very important figures in any Washington administration, particularly in Democratic White Houses, for the Democrats are the party of lawyers. In theory, attorney generals can be fired - like anyone else in the administration - but in practice it is difficult to do so, particularly when it looks like the president wants something covered up. Richard Nixon, who dispensed with his shortly before the climax of the Watergate scandal, could speak eloquently from the grave to Mr Obama on this subject.
When earlier in the summer, Mr Holder saw the classified accounts of CIA abuses, the waterboarding and wall slamming, and most particularly the unexplained deaths of prisoners in US custody, he concluded that Mr Obama's stated preference to look forward, not backwards, was unsustainable. This week he appointed a career prosecutor to look into the accounts to see what needed to be done. Thus, Mr Panetta has lost the turf war, a point that became clear during a lively telephone conversation he had with Mr Holder, which required the chief of staff later to brief reporters that only one expletive was used by the CIA director, and not a bad one.
Mr Holder's decision to appoint the prosecutor was motivated in part by his reading of a 2004 internal CIA investigation into aggressive interrogation techniques, which was finally made public this week after court challenges, with much of its detail blacked out. However, the outlines were certainly shocking. One prisoner was threatened that his family would be killed if he failed to co-operate. In another case, CIA interrogators took a power drill and gun into the cell of a Saudi, Abd al-Rahim al-Nashiri, who was suspected of involvement in the blowing up of the USS Cole in 2000. He was threatened with violence from the drill and the gun, and video tapes of his interrogation were subsequently destroyed, which is now the subject of a separate investigation.
In another case, a shot was fired in a neighbouring cell to convince a detainee he was about to be executed, a form of abuse which is specifically banned by US authorities. The big question is, how far up the chain of command does Mr Holder want to go? And how much might Mr Obama do to try to stop him? The politics of this are fascinating. The last thing Mr Obama wants in the midst of an increasingly partisan fight in Congress over his health reforms is a punch-up with the former Republican administration. But it looks as though he is going to get one whether he likes it or not.
The former vice president Dick Cheney, perhaps fearful that the prosecutor's searchlight might eventually point in his direction, says the appointment fuels "doubts about this administration's ability to be responsible for our nation's security." "The people involved deserve our gratitude," Mr Cheney said, adding that the CIA's aggressive interrogation techniques were directly responsible for sparing Americans further terrorist attack. This is a bold assertion, and one which comes close to saying that torture is justified if the ends are important enough.
It is not an argument any defence attorney would want to hear from his client in the dock. It also runs contrary to what the more honest interrogators at Abu Ghraib subsequently conceded, which is that torture - especially long after capture - tends to yield "false positive" information from a victim who will say anything if his interrogator will then let him breathe again, or switch off the electric current running through his testicles.
But being "weak on terror" is a toxic charge to level at a Democratic president, especially the first black president, a politician with a liberal voting record in the US Senate, and with the middle name of Hussein. Being seen as soft is a problem for any Democrat; should there then be a further terrorist attack on America while this debate is being played out, it could prove politically disastrous, even fatal.
"Stuff happens" was Mr Rumsfeld's infamously blithe response to the wave of looting of Iraq's museums after the invasion. But that can also be applied more generally to the cut and thrust of Washington politics, and there is no doubt that partisan antagonisms have returned, with a vengeance. This week some of the more brutal CIA interrogators may be feeling nervous because of the attorney general's victory; some formerly highly placed Republicans may also now have sweaty palms. But Barack Obama is smart enough not to feel smug, and to know that when "stuff happens" in Washington DC it can cut both ways.
* The National