The three Azzawi brothers, Hussein, Qadam and Ali, loved their home. Their late father had picked the two-storey villa because it was big enough for his sons to marry and raise children in. He hoped that they would always live there.

That dream ended with a letter, dumped after dark on the Azzawis’ doorstep. The death threat was organised like a business memorandum, with the helpful heading “Subject: displacement”.

It read: “An eye for an eye, a tooth for a tooth. You should leave the Sunni areas, including Ghazaliyah, within 24 hours. Otherwise your heads will be cut, your houses and furniture will be burnt just as the militias have done to the Sunnis . . . Signed: al-Qaeda in the land of two rivers and the Mujahidin Shura Council.”

Two gunmen had walked down the street like postmen and dropped the letter off at every Shia home. Once they had covered the block, a car picked them up.

No one should have been surprised. Things had worsened since the bombing of a Shia shrine in Samarra 10 months ago triggered widespread Shia-Sunni violence. About 420,000 people have since been displaced across Iraq; 1.6 million have fled the country since 2003. The large-scale expulsion of Sunnis and Shia has been redrawing Iraq’s map.

The trend of religious and ethnic cleansing has overwhelmed Baghdad. “Maybe at the beginning we thought the neighbourhood bonds between Sunnis and Shia were stronger and able to overcome the intimidation factors,” said a Western diplomat. “But at this point, it is a little bit more of every man for himself.”

The al-Qaeda threat said that the expulsions were in revenge for similar attacks by Shia militias, that Sunnis had been killed, kidnapped and displaced in Mahmudiyah, Rashadiyah, Shaab, Shaoula and Hurriyah.

On November 19, on the evening that the Azzawis received the letter, Qadam looked out of his window to see nine families fleeing the neighbourhood — too frightened to wait until morning. They headed on foot for the Shia enclave of Shaoula, directly to the north (the Azzawis’ street sits right on the dividing line). Shaoula was controlled by the Shia Mahdi Army militia, which had been raiding Ghazaliyah for months. Qadam remarked bitterly that the normal Iraqi army checkpoints had disappeared that evening on his way home. They always did when there was trouble.

The Azzawis were now the last Shia family on their street. They had doggedly hung on for the past year as shadowy Sunni groups pushed to purge Ghazaliyah of Shias. They had watched others flee after getting similar death threats, but the family had always convinced themselves that they were safe.

The al-Qaeda letter changed everything. Their 62-year-old mother could not bear to leave her late husband’s home. He had died the year before from a heart attack, but she told her sons: “I’m not worried about me, it’s you. All of you are coming and going in the morning and afternoon. It’s too dangerous.”

That night, the brothers guarded their home. “We watched the road. Qadam was on the roof. I was in the main door and my brother Ali was in the other window until the sun came up,” Qadam’s older brother. Hussein. told The Times.

()Hussein and Ali’s wives and their three sisters packed important papers and food. Their mother, already suffering from chronic asthma, sobbed in her room, clutching a picture of her beloved husband. Hussein’s two infant daughters and Ali’s little boy and girl slept, oblivious to the turmoil. Hussein spoke by phone every half hour with their brother-in-law, who lived on a neighbouring street.

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