Its brand of pro-Shiite activism had the side effect of pitting Iraqis against each other, helping to stir worries of civil war.

That seems an inaccurate description of Sadr's movement. His was one of the only groups that reached across religious lines, providing aid to Sunni Iraqis during the US siege of Falluja. His militia activities have been mostly concentrated against rival Shia factions like Badr, who were the ones (alones with AQI) who were stirring things up for a civil war.

(This, by the way, is one reason why the Surge -- when it comes to actually having the power to keep Iraq from blowing to kingdom come in the near future -- has really done very little, and never could have. The other is that our Dear New Sunni Friends are surprisingly open nowadays in telling reporters and US military men both that they'll return to fighting the government and the US unless they get bribed a lot more, and that they're planning anyway to simply wait us for us to leave and then start using all those nice new weapons they bought with our money against the Shiites. What the Surge HAS done is kick the whole problem down the road for the next President to deal with, relieving Bush of any responsibility to deal with the explosion.)