With a Thousand Words to Say...and Then Some: October 2007

2002-03 - U.S. makes case that Saddam Hussein has weapons of mass destruction (WMDs).
March 20, 2003 - U.S. leads invasion of Iraq.
May 1, 2003 - George W. Bush declares the end of major combat operations (the infamous "Mission Accomplished" banner).
May 2003-June 2004 - U.S. establishes a military occupation of Iraq run by the Coalition Provisional Authority (CPA).
Fall 2003 - The Iraqi insurgency begins. Members of the Iraqi army and secret police, who stayed underground when the U.S. invaded, form guerilla units and start attacking U.S. troops.
June 2004 - CPA turns control over to an interim Iraqi government which is overseen by the CPA.
January 2005 - The Iraqi interim government is replaced by the Iraqi National Assembly as a result of national elections.
May 2005 - Suicide bombings tear through Iraq making for the bloodiest month in Iraq to date. Most of the attacks are perpetrated by Sunni Arabs against Shias.
February 22, 2006 - The Shiite Al Askari Mosque is blown up by 5-7 men dressed as Iraqi special forces (believed to be Sunnis). Shiites across Iraq respond by blowing up Sunni mosques and killing dozens. Sectarian tensions had already been mounting, and this incident is widely considered the official start of the Sunni-Shia civil war in Iraq.
November 2006 - Democrats regain control of both the House of Representatives and the Senate in U.S. Congressional elections. The main motivating factor for U.S. voters in the elections is the Iraq War.

The reason given for the invasion was that Iraq had WMDs. Since WMDs were not found, many people now believe the intelligence about WMDs was misrepresented or falsified in order to justify going to war.
Americans were not prepared for a long war. They had been told it would last weeks or months at the most. At the time of the 2006 elections the war had been raging for 3.5 years and there was no end in sight.
The stated goal was for U.S. forces to train and hand over authority to an Iraqi army. This goal was far short of being reached, and voters felt that putting Democrats into Congress would speed this up and get U.S. troops out of Iraq.

December 6, 2006 - A bipartisan group of U.S. foreign policy experts called the Iraq Study Group releases a report detailing the situation in Iraq, and making suggestions for a change in course of action.
January 10, 2007 - In a primetime televised speech to the American people, George W. Bush completely ignores the recommendations of the Iraq Study Group, and instead shockingly announces a troop surge: the addition of 21,500 U.S. troops in Iraq.
September 10, 2007 - General David Petraeus, the officer tasked with commanding the surge by President Bush, testifies before Congress that roughly 30,000 U.S. troops can be withdrawn by the summer of '08, and possibly more after that depending on conditions on the ground.
September 14, 2007 - President Bush, in a televised address to the nation, announced that there would be a limited withdrawal of U.S. troops. 5,700 personnel would return home by Christmas '07, and a total of 21,500 would return home by July '08, thus returning the U.S. force in Iraq to the pre-surge level.
1. People paying attention to the war up to this point know this decision is much ado about nothing. Tours of duty for U.S. soldiers have already been extended from 12 months to 15, and unless those tours are to be extended even further, Bush had no choice but to reduce the number of U.S. forces in Iraq back to pre-surge levels by summer 2008.

With a Thousand Words to Say...and Then Some