BAGHDAD — Brig. Gen. Heidi Brown made history during the 2003 invasion of Iraq as the first female commander to head an American combat brigade in wartime.

The imposing, 49-year-old Texan led battalions providing air cover and artillery support to U.S. ground forces fighting their way toward Baghdad across Iraq's southern desert. Her troops shot down Iraqi scud missiles. Several of her soldiers, including Pfc. Jessica Lynch, were ambushed and taken hostage, in the first major crisis of the early days of the invasion.

Her new deployment, which began during the spring, is similarly high-stakes, but could hardly be more different.

Brown's new job title — commander in charge of the responsible withdrawal — derived from President Obama's campaign vow to end an unpopular war in a way that does not upset the delicate balance that has allowed a measure of normalcy to return to Iraq.

"So that was then, fighting our way up the desert, all the way up to Baghdad," she said in a recent interview, sitting in an office inside a palace built for Saddam Hussein. Now, "I work in the palace. It's just very different. Here I am, planning the responsible withdrawal and moving all this stuff out of theater."

By the end of next summer, only six major U.S. military hubs and a couple of dozen smaller bases will remain, Brown said. All American troops must be out of Iraq by the end of 2011.

Senior American commanders have said they want to keep a robust force in Iraq through the January 2010 national election and the following few months because they fear political tension could trigger violence. Between now and April, the force will be reduced to roughly 90,000 troops. It will then contract more quickly, to meet the 50,000-troop target by August 2010.

U.S. commanders expect to rely heavily on Iraqi security forces to keep them safe as they depart, an irony not lost on Brown recently when she asked an Iraqi general if he had been in the army in 2003. The general said yes.

"I looked at him and I asked, 'If you had seen me in March 2003, would you have shot me? Would I have shot you?' " Brown said.

In all likelihood they would have. Now they must work together.