At the height of the sectarian violence in Iraq in 2006 that followed the coalition invasion, more than 2500 people were killed a month, every month, for a year. The excesses of the time are well covered by the writers who were there. To the background of ritualised slaughter from Al-Qa'ida in Iraq and the Jaysh al-Mahdi, smaller militias sprang up in every community to man the roadblocks and carry out the patrols that guaranteed their homes some small shred of security. As these militias fought and protected themselves from other militias, so they become more brutal. Roadblocks became death traps, and the ranks of those disappeared at night grew. Shi'a militias developed a fine line in drilling holes in the heads of those they captured. Sunnis used the power drill for other forms of torture. Each new morning found more bodies abandoned in wastelands. And as the violence grew, so the various sects of Islam in Iraq retrenched territorially and ideologically; the country became split, physically and politically, along sectarian and tribal lines.