The history of Iraq since the overthrow of Saddam Hussein has been full of fake turning-points - the capture of Saddam in 2003, the supposed handover of sovereignty to Iraqis in 2004, the parliamentary elections and referendum in 2005. All these events were greeted by the White House and Downing Street at the time as important and encouraging signs of progress, justifying the invasion of 2003. But with every year the war has become more intense. Iraqis are now dying at the rate of about 1,000 a week, according to the UN. Civil war is raging in central Iraq. The war against the US soldiers has also escalated, though American casualties are far lower. The country is awash with blood.
There were two real turning-points of very different kinds in Iraq in 2006: the blowing up of the Shia al-Askari shrine in Samarra on 22 February; and the Republican defeat in the US mid-term elections, in which Iraq was the main issue, on 7 November. The first was the starting gun for the present sectarian bloodbath. The second also had a vast effect within Iraq as the US began to contemplate failure.
In Samarra, nobody was killed by the explosion itself, though it wrecked the great golden dome of the shrine. But the attack led to a Shia onslaught on Sunni Arabs. Shia restraint, already close to breaking point, finally gave way after more than two years of bombs aimed at army and police recruits, who were mostly Shia, as well as at purely civilian targets. Within days, 1,300 people, mostly Sunni, were dead. People caught in the wrong areas at the wrong time were dragged from their cars and slaughtered.
Amid this bloodbath, it is difficult to pick out long-term trends. However, several were clearly visible in 2006:
* There is civil war between Shia and Sunni in central Iraq, and it is getting worse by the day. The most important battle is for control of Baghdad.
* The US is becoming weaker in Iraq because of its evident failure to gain control of the country, and because of the Republicans' defeat in the mid-term elections. The number of Americans who support continuing the war is decreasing.
* The US tried, under its astute and affable envoy Zalmay Khalilzad, to conciliate the Sunni by offering them positions in government, limiting provisions in the constitution they disliked and seeking to talk to the insurgents. The strategy shows little sign of working, and Khalilzad's star is waning.
* The Shia, never comfortable with the US-led forces but prepared to work with the US for their own ends, are increasingly hostile to the occupation. The percentage of Shia who agree with armed attacks on US-led forces rose from 41 per cent to 62 per cent in the first nine months of 2006.
* The US is considering negotiations with Iran and Syria, though this would be a confession of weakness. It also knows that they would look for concessions, such as a US withdrawal and an increase in their regional influence. Sunni powers like Saudi Arabia, Jordan and Egypt are increasingly worried by Shia successes in Iraq and Lebanon.
* The Kurds are losing confidence that Iraq will hold together, though they do not want to be blamed for it coming apart. Kurdistan is the only peaceful part of Iraq.
* The militias grew stronger during the year because the army and police cannot provide security.
Iraq is disintegrating. In areas where there was a mixed population - above all in Baghdad itself - there have been mass killings. After the Samarra bomb, the capital began to divide up into hostile districts, each protected by its own militiamen. The militias themselves became stronger as everybody wanted armed men they could trust at the end of their street. Shia and Sunni families - whichever was in a minority - received letters, often enclosing bullets, telling them to move within 24 hours or be killed. Few dared to stay.
By the end of the year, the UN High Commission for Refugees estimated that 1.6 million Iraqis had fled within the country and another 1.8 million had gone abroad, mostly to Jordan and Syria. At one point, an estimated 1,000 people a day were crossing the border into Jordan and a further 2,000 a day into Syria.
Can anybody put Iraq back together again? As Iraqi and American politicians announced that they opposed partition, the country was undergoing de facto division. The worst fighting was in places like the fruit-growing province of Diyala, where Sunni and Shia are evenly balanced in numbers. The chief of police in the provincial capital Baquba estimated that 9,000 people had been killed, mainly Shia. Sectarianism penetrated everywhere. There is one Iraqi army division in Diyala but it is almost entirely Shia. It only arrests Sunni. The same pattern is seen across Iraq.
In Baghdad, people in the Sunni enclave of al-Adhamiyah demanded that an army battalion be moved from their area because it was Shia. The Sunni regard the Baghdad police and police commandos as Shia death-squads in uniform.
Shia-Sunni hostility is not the only reason why Iraq is breaking up. In the northern city of Mosul, 70,000 Kurds have fled, fearing assassination by Sunni gunmen. In the Shia bastion of Basra,the few Sunni are escaping.
Inside Baghdad, it is the Shia who are advancing, using their superior numbers. Sunni are being pushed back into the south and west of the city. But in the furthest outskirts, in dusty towns that were once mixed, the Sunni are on the attack. There is brutal fighting in towns such as Balad, one of the few places with a Shia majority north of Baghdad, and Mahmudiyah, on the main road to the south. The Sunni are increasingly in a position to encircle Baghdad.
The US troops are largely bystanders in this ferocious civil war. Where they do intervene it is usually to defend the Sunni, angering the Shia. It is a nasty feature of present-day Iraqi politics that Sunni, Shia and Kurds all see themselves as victims and have little sympathy for or knowledge of the woes of others. In conversation, they tell of atrocities committed against their own community but scarcely mention the killings perpetrated by their own militias and gunmen. Shia describe their Sunni opponents as "Wahabis" and cat's-paws of Saudi Arabia, while Sunni view Iraqi Shia as pawns of Iran.
By the end of the year, the US was desperately casting around for a policy. It is not easy. US control is slipping. Iraqis and neighbouring countries alike can see it. But President Bush - with Tony Blair trailing behind - still stoutly maintains that they will "stay until the job is done". They speak of training and equipping the Iraqi army and police. But the problem is not training or equipment, but loyalty. The Kurdish leaders believe that the army and police would split if they were ever used against their own community. When the British withdrew from their base, called Abu Naji, in Amara in August and handed it over to Iraqi security forces, it was promptly looted.
Worse, the US is still toying with some very dangerous ideas. For instance, on 8 November the US National Security Adviser, Stephen Hadley, in a memo about the Prime Minister of Iraq, Nouri al-Maliki (which was promptly leaked to the US press), suggested that the prime minister turn on Muqtada al-Sadr, the nationalist Shia cleric, and his Mehdi army militia. The other militias are not mentioned. But Maliki can hardly attack his own community. Shia Iraqis, perhaps 16 million out of the 27 million Iraqi population, suspect that the US is trying to rob them of the victory they won in the two elections in 2005. Khalilzad did his best to conciliate the Sunni, but without much effect.
It is difficult to see an alternative to the present Shia-Kurdish alliance - 80 per cent of the population - ruling Iraq. The elections showed that there are few secular moderate Iraqis. Friends of the US are often seen as American pawns.
During the first part of the year, the US put great effort into getting rid of Ibrahim al-Jaafari and replacing him with Maliki. It was unclear why Washington thought this would do them much good. In the event, both prime ministers this year have proved very similar. Neither can do much because their governments - like that of Lebanon - are made up of ministers who represent their community or party. The appointment of these ministers is the fruit of prolonged negotiations. They cannot be fired easily for corruption or incompetence. Ministries have become bastions - and a source of money and jobs - for the party running them. In November, the police commandos from the Shia-controlled Interior Ministry stormed the Sunni Higher Education Ministry and took 150 prisoners. The Ministry of Health is controlled by supporters of Muqtada al-Sadr. Doctors from other communities are commonly dismissed or forced out.
Some things did not change in Iraq in 2006. Supplies of electricity, water, gasoline and kerosene remain inadequate. Prices went up. In the heat of the summer, there is not enough power for the air conditioners. Iraqis rely on small generators, but the rise in the cost of fuel has made them prohibitively expensive. Iraqis asked by foreign reporters about the verdict in the Saddam trial, or some speech by President Bush, often respond that their only priority is to keep themselves and their families alive. They regard their own government as a parasitic body interested primarily in extracting bribes to evade deliberately complicated red tape.
The Republicans' loss of both Houses of Congress on 7 November is affecting Iraq greatly. For a start, the White House will be subject to far more criticism. The US media has been emboldened. Some networks have started calling the violence a "civil war" - as it is. The Iraq Study Group under James Baker is to produce new proposals.
But the outcome may be less productive than many expect. There is talk of involving Iran, Syria and other neighbours of Iraq, whose governments Washington was threatening to overthrow only two years ago. But the conversion of the White House to such diplomacy is very uncertain.
And it is a mistake to think that either the Sunni insurgents or the Shia militias are under the full control of Damascus or Tehran - though both have influence. The Democrats are as incoherent on Iraq as the Republicans, but both are intent on not being blamed for any disasters to come.
What options are open to the US? It could reinforce its troops with 20,000 to 30,000 more men, but these numbers add little security in a city the size of Baghdad. It could pull back to its bases, prepared to intervene in support of Iraqi government forces. But these bases depend on vulnerable supply lines. It could pick a fight with the militias, notably the Mehdi army of Muqtada al-Sadr, as it did before in 2004 - it would win militarily, but it cannot eliminate the Sadrists because they are too numerous and too popular.
Negotiations are unlikely to succeed that do not have at their centre an agreement for a timetable for US and British withdrawal. It is their presence in Iraq that is destabilising the region. Their departure should also be unambiguous, with no American bases established inside Iraq.
The US and Britain have argued that this would lead to the Iraqi government unwinding, and would embolden the insurgents. But both these processes are going on already. Sunni resistance to the occupation has created a sympathetic environment for al-Qa'ida-type organisations to flourish in central Iraq. The longer the war goes on, the more entrenched the fanatical Islamic groups will become.
The last justification for keeping US troops in Iraq was that "at least they prevent civil war", but they are failing to do so. It might be useful to have foreign forces acceptable to both sides, but the US and British occupiers do not, in the eyes of Iraqis, have the legitimacy to act as mediators.
There is one sign of hope for Iraq, which appeared after the mid-term elections. Previously, US political and military actions in the country were geared primarily to making political gains in the US. Whatever the disasters in Iraq, President Bush was able win re-election in 2004 and keep control of both Houses of Congress - no mean achievement.
Even sensible decisions were tainted by the US political agenda. It was reasonable to hold parliamentary elections in 2005, but unwise to do so before all three Iraqi communities had agreed the rules of the political game. Even in the last hours before the US mid-terms, Iraq was being milked for political advantage by the White House. The guilty verdict on Saddam had been due on 16 October, but was mysteriously postponed to 5 November, the last full news cycle before election day. With the White House now facing a hostile Congress, this type of manipulation of Iraqi politics will come under far greater scrutiny.
The coming year is likely to see the battle for Baghdad intensify. Iraq will probably continue to exist, but as a loose federal state. The Kurds always wanted this; indeed, they would like independence if they dared to take it, but they fear the reaction of Turkey, Iran and Syria.
After the horrors of this year, Sunni and Shia will hardly be able to co-operate closely in future. The sense of Iraqi identity may have been damaged beyond repair. But, more than most states, Iraq is dominated by its capital and Shia and Sunni will continue to fight to rule Baghdad until they either win or know there is no hope of victory.
'The Occupation: War and Resistance in Iraq', by Patrick Cockburn, is published by VersoReuse content