The New York Times has nice synopsis of the War in Iraq. The LA Times has a great timeline, some of which I've copied here:
Oct. 11, 2002 -- Force authorized
Congress authorizes the use of force against Iraq. Ending a somber debate that pushed past midnight, the Senate votes, 77 to 23, for the resolution. The action came hours after the House gave its approval on a 296-133 vote.
Nov. 8, 2002 -- U.N. ultimatum
United Nations Security Council passes Resolution 1441 calling on Iraq to cooperate with weapons inspectors. The show of international unity sends a strong message to Iraqi President Saddam Hussein that he is without allies if he continues to defy the United Nations, ambassadors said.
Jan. 28, 2003 -- ‘Imminent threat’
Speaking to a skeptical world, President Bush in his State of Union address gives a forceful and detailed denunciation of Iraq. He promises new evidence that Saddam Hussein’s regime poses an imminent danger to the world and demands the United Nations convene in just one week to consider the threat.
Feb. 5, 2003 -- Colin Powell at U.N.
Secretary of State Colin Powell argues before the Security Council that the U.S. has evidence of weapons of mass destruction in Iraq, based on information provided by source codenamed “Curveball,” who later admitted to lying.
March 17, 2003 -- Bush’s ultimatum
President gives Saddam Hussein a 48-hour deadline to leave Iraq or face sure destruction “at a time of our choosing.”
March 20, 2003 -- U.S. Forces Enter Iraq
U.S. and British troops sweep into southern Iraq in an invasion aimed at Baghdad, where a new wave of missiles and bombs struck a presidential compound housing several government departments at the heart of Saddam Hussein’s power.
April 9, 2003 -- Baghdad falls
U.S. troops break Saddam Hussein’s 24-year grip on Iraq. With help from the Marines, Iraqis topple a four-story statue of the president. Looting of government and public buildings, including museums and armories, ensues unchecked amid mass disorder.
May 1, 2003 -- ‘Mission accomplished’
Aboard USS Abraham Lincoln, President Bush tells a cheering crew that U.S. forces have brought about a ‘turning of the tide’ against terrorism. Underneath a banner reading “Mission Accomplished,” the president says the conflict with Iraq marked the beginning of “a new era” in waging war.
Dec. 13 2003 -- Hussein caught
Saddam Hussein was captured by American forces at a farmhouse in ad-Dawr near Tikrit in a hole in Operation Red Dawn.
June 28, 2004 -- Iraqis take power
Led by Prime Minister Iyad Allawi, an interim Iraqi government takes power from U.S. administrator L. Paul Bremer III after a furtive ceremony meant to preempt insurgent attacks that could have disrupted the hand-over.
Jan. 30, 2005 -- Iraqis vote
Millions of Iraqis defy violence, calls for a boycott and a legacy of despotism to cast ballots in the nation’s first multiparty elections in half a century.
Dec. 30, 2006 -- Hussein executed
A defiant Saddam Hussein is hanged at dawn in a secret concrete death chamber. Before his execution, he denounces the West and Iran.
Jan. 10, 2007 -- Troop surge
President Bush acknowledges that his previous strategy has failed and announces the U.S. needs to add more than 20,000 troops in order to avert defeat.
Aug. 19, 2010 -- Combat troops leave
The last of U.S. combat troops withdraw from Iraq. The move comes amid a deep political crisis that many think could turn increasingly violent, and Iraqis are deeply apprehensive.
According to then Defense Secretary Donald Rumsfeld, "Our exit strategy in Iraq is success; it's that simple. The objective is not to leave [but] to succeed in our mission."
President Bush tapped Lieutenant General Jay Garner to lead the transition in Iraq. His strategy -- which quickly led to his ouster -- was to maintain the same state institutions that operated under Saddam, although many (including many Iraqis) wanted a clean slate. The problem was "Excluding all 1.5 million party members from the new government would mean shutting out virtually every public servant, precisely the people who know how to get things running again." Garner's logic was: "As in any totalitarian regime, there were many people who needed to join the Baath Party in order to get ahead in their careers. We don't have a problem with most of them." American forces would work to identify the nefarious elements within the state and bring them to justice. To prepare Iraq for a quick American exit, Garner pushed ahead with a plan to have national elections as soon as possible (within as ninety days of the fall of Saddam) that would install a new Iraqi government. The general was swiftly replaced by L. Paul Bremmer. After his ouster, reports stated Garner said "he fell out with the Bush circle because he wanted free elections and rejected an imposed programme of privatisation."
The resulting policy of de-Ba'athification proved disastrous. The the International Center for Transitional Justice's:
research and interviews with the official body that led de-Baathification initiatives for much of this period showed that these wholesale dismissals, combined with a lack of due process, badly undermined Iraq's government and military structures and fuelled a sense of grievance among those affected - not just employees, but also their families, friends and communities. It is unsurprising that the process became a significant contributing factor in widespread social and political conflict.The Iraqi military was especially affected by de-Ba'athification, which resulted in the dismissal of up to 500,000 soldiers. Ultimately, the decision to disband the army fueled a growing insurgency.
In the aftermath of CPA Orders 1 and 2, Ba’ath officials became natural allies to the angry and financially troubled ex-soldiers of the Iraqi Army after the Army was disbanded, with no effort made to recall those former soldiers who may have remained interested in serving. The ability of senior Ba’ath leaders to obtain and provide funding to the insurgency was particularly important in helping to organize it into an effective force able to include unemployed and desperate Iraqis willing to strike at U.S. forces for money.
Seven years, over 130,000 civilians, and more than $2 trillion dollars spent, the last american combat troops left Iraq in August 2010. And for all that blood and treasure, the United States gained little. A study conducted by the Costs of War Project by the Watson Institute for International Studies at Brown University:
concluded the United States gained little from the war while Iraq was traumatized by it. The war reinvigorated radical Islamist militants in the region, set back women's rights, and weakened an already precarious healthcare system, the report said. Meanwhile, the $212 billion reconstruction effort was largely a failure with most of that money spent on security or lost to waste and fraud, it said. [Ibid]
Given the traumatic experience we've had in Iraq, it's worthwhile to ask: How has Iraq changed us? And for that analysis, I defer to Dan Drezner:
Here's the thing: Deep down, the American people are pretty realist. The legacy of Operation Iraqi Freedom is that this realist consensus has cemented itself further in the American psyche. The American public has an aversion to using force unless the national interest is at stake, and a deep aversion to using force to do things like promote democracy or human rights. . . .
It took a generation and the end of the Cold War for the lessons of Vietnam to fade away. I'd wager that it will take at least a generation for the legacy effects of the Iraq War.
Indeed, in American history, the war that Operation Iraqi Freedom reminds me of isn't Vietnam -- it's the War of 1812. That was another war of choice that was launched in no small part because of War Hawks in the halls of Congress. It went disastrously for the United States save the Battle of New Orleans, which allowed politicians to put a gloss of victory on an otherwise calamitous conflict. The long-term political effects on some of the War Hawks were pretty severe however (see: John C. Calhoun).
Operation Iraqi Freedom's effects on the international system were minor at best. The effects on American foreign policy, however, are significant and will be with us for some time to come.That conclusion is all the more instructive given the the number of conflicts around the globe in which the United States could become involved: North Korea, East and South China Sea disputes, Taiwan/China, Syria, Iran's nuclear program. The list goes on.
 Brian Bennet, et al. Sorting The Bad From The Not So Bad. Time. May. 19, 2003; available at: http://www.time.com/time/magazine/article/0,9171,1004842,00.html
 David Leigh. General sacked by Bush says he wanted early elections. The Guardian. March 18 2004; available at: http://www.guardian.co.uk/world/2004/mar/18/iraq.usa
 Iraq's de-Baathification still haunts the country. Al-Jazeera. March 12, 2013; available at: http://www.aljazeera.com/indepth/opinion/2013/03/201331055338463426.html
 W. Andrew Terrill. Lessons of the Iraqi de-Ba'athification Porgram for Iraq's Future and the Arab Revolutions. Strategic Studies Institute. May 2012; available at: http://www.strategicstudiesinstitute.army.mil/pdffiles/PUB1106.pdf
 Alissa J. Rubin and Damien Cave. In a Force for Iraqi Calm, Seeds of Conflict. The New York Times. December 23, 2007; available at: http://www.nytimes.com/2007/12/23/world/middleeast/23awakening.html?pagewanted=all
 Daniel Trotta. Iraq war costs U.S. more than $2 trillion: study. Reuters. March 14, 2013; available at: http://www.reuters.com/article/2013/03/14/us-iraq-war-anniversary-idUSBRE92D0PG20130314