In his prime-time speech to the nation, Obama claimed no victory and said the United States "has paid a huge price" to give Iraqis the chance to shape their future. That toll has included more than 4,400 dead, tens of thousands of troops wounded and hundreds of billions of dollars spent since March 2003.
"Ending this war is not only in Iraq's interest - it is in our own," Obama said.
Yet for all the finality, the war is not over, and the American sacrifice will continue.
Obama is keeping up to 50,000 troops in Iraq for support and counterterrorism training, and the last forces are not due to leave until the end of 2011 at the latest. Still, he sought to mark Aug. 31, 2010, as a milestone in one of the defining chapters in recent American history.
In a telling sign of the domestic troubles weighing on the U.S., Obama reserved part of his war address to campaign for his efforts to revitalize the economy.
On a night focused on his role as commander in chief, he said his "central responsibility as president" was to get people back to work.
The ending of the combat mission on this date had been known for 18 months. Given the stakes, the toll in American lives and dollars and the long consuming debate, Obama sought to explain it to the country.
"Operation Iraqi Freedom is over, and the Iraqi people now have lead responsibility for the security of their country," Obama said. He made sure to remind the nation that he had promised to meet this goal and shrink U.S. involvement by now, "and that is what we have done."
Obama's rise to the presidency was built in part on his fierce opposition to the war, an American-led endeavor that lost public support as it rolled on and American casualties rose. Obama has long held that the war inflamed anti-American sentiments abroad and stole resources from the fight in Afghanistan.
In a defense of his foreign policy, Obama said capping the combat mission in Iraq would send a message to the world that the U.S. "intends to sustain and strengthen our leadership."
Obama sought to close a divisive chapter without declaring victory.
His opposition to the war presented him with a tricky moment - standing firm in his position without disparaging the sacrifice and courage of those who fought.
On Tuesday he was intent on assuring the nation and the stretched military that all the work and bloodshed in Iraq was not in vain, declaring that because of it "America is more secure."
Though the U.S. commitment in Iraq is winding down, Obama is sending more troops to Afghanistan, the home base of the Sept. 11, 2001, al-Qaida terrorists, where Americans have been fighting for nearly nine years.
"It is going to be a tough slog," Obama said of Afghanistan in remarks earlier Tuesday to soldiers at Fort Bliss, Texas. Defense Secretary Robert Gates said success in Afghanistan was possible but "is not inevitable."
Tuesday night, the president's speech was never intended to be celebratory.
"It's not going to be a victory lap," Obama said at Fort Bliss, a post that has lost 51 soldiers in the Iraq war. "It's not going to be self-congratulatory. There's still a lot of work that we've got to do to make sure that Iraq is an effective partner with us."
In fact, Iraq is in political turmoil, its leaders unable to form a new government long after March elections that left no clear winner. In Baghdad on Tuesday, Vice President Joe Biden pressed Iraqi leaders anew to break the impasse. The uncertainty has left an opening for insurgents to pound Iraqi security forces, hardly the conditions the U.S. envisioned for this transition deadline, which Obama announced 18 months ago.
Since the war began, more than 4,400 U.S. troops have been killed and almost 32,000 have been wounded. The war is one of the longest in the nation's history, even as the one in Afghanistan continues.
Obama's big day was defined by what it was - a turning point, a promise kept - and by what it was not.
It is not the end of the war. More U.S. troops are likely to die.
All U.S. troops are not expected to leave Iraq until the end of 2011, a final agreement that was secured before Obama took office.
Obama has accelerated the end of the U.S. role in Iraq by pulling home nearly 100,000 troops.
The American public has largely moved on. The prevailing worry now is joblessness at home.
Almost forgotten are the intense passions and protests that defined the Iraq debate through much of the past decade. Or that lawmakers of both parties authorized President George W. Bush to go to war.
What emerged was not just a war but a Bush doctrine of pre-emptive force against perceived threats, one that reshaped how the world viewed the United States. In Iraq, the intelligence that made the case for war was faulty; no weapons of mass destruction were ever found.
Saddam Hussein was toppled, and Iraqis now live in greater freedom, but those were not the rationales for war. The aim was, as Bush put it in his own Oval Office address in 2003, "to defend the world from grave danger."
The national focus has turned to Afghanistan and to the staggering economy in the U.S. In particular, weeks ahead of a vital congressional election in the U.S., Obama wants Americans to see a linkage between getting out of Iraq and investing more money at home.
A major thrust of Obama's speech was to honor the service of U.S. troops and civilian workers in Iraq. Another was to assure Iraqis that the United States is not abandoning them.
And yet another mission was to remind the country, in Obama's view, about where the true threats to national security lie, including in Afghanistan.
Just 38 percent of people support the war in Afghanistan, according to a new Associated Press-GfK poll, and only 19 percent think things will get better in the next year. On Iraq, unsurprisingly, Obama finds more support in pulling troops home: 68 percent approve of his ending the formal combat mission.
The cost has been financial, too. Congress has allotted more than $1 trillion for both wars.
The Iraq war linked Obama and Bush before the Democrat won the White House, and has ever since.
Fittingly, Obama called Bush on Tuesday to talk about this moment in the war. It is more than seven years after the former president declared that major combat operations were over.
The White House said the call was private and would not say more.