September

From Atrios:

Four months ago today a "Deadline-Free War Funding Bill" was passed. This bill was passed after Bush started going on the teevee saying that if Congress didn't pass it quickly then troop deployments would have to be extended. This didn't make any sense, but that didn't stop the media from reporting it. Then someone at the Pentagon leaked the fact that troop deployments were going to be extended anyway. At which point everyone forgot that Bush was trying to blame this on Congress.

Since then, approximately 354 US troops have been killed looking for little Tommy Friedman's ponies.

There's also this:

CNN:

Diyala province -- which sprawls north and east of Baghdad -- has been a major front in the Iraq war since the U.S. troop escalation called the "surge" began earlier this month. U.S. and Iraqi forces in recent months have embarked on offensives targeting al Qaeda in Iraq.

So the surge began in September! It all makes sense now.