Timeline: Important Events of the War in Iraq

ByABC News

March 18, 2007 — -- This week marks the fourth anniversary of the U.S. war in Iraq, and ABC News is taking another look at "Where Things Stand" in its special series of the same name.

Following is a timeline of notable events in the four years of the Iraq war.

March 17, 2003 -- President Bush gives Saddam Hussein and his sons 48 hours to leave Iraq.

March 19, 2003 -- U.S.-led invasion begins.

March 21, 2003 -- "Shock and awe" campaign begins.

April 1, 2003 -- Pfc. Jessica Lynch is rescued.

April 9, 2003 -- "Fall of Baghdad," as statue of Saddam Hussein gets toppled in the city's center.

May 1, 2003 -- On board the USS Abraham Lincoln, President Bush makes his "Mission Accomplished" speech, declaring and end to major military operations.

July 22, 2003 -- Saddam's sons Uday and Qusay killed in a U.S. raid on a house in Mosul.

Dec. 13, 2003 -- In a "spider hole" near Tikrit, Saddam Hussein is captured by U.S. troops. He surrenders without a fight.

March 31, 2004 -- Four American civilian contractors from Blackwater USA are killed by Iraqi insurgents in Fallujah. Their mutilated bodies get dragged through the streets before being hung over a bridge.

April 29, 2004 -- Photos of abuse at Abu Ghraib prison are released, first seen in a report on "60 Minutes II."

May 8, 2004 -- The decapitated body of Nick Berg found. Three days later (May 11), video of his beheading is posted on an Islamic Web site.

June 28, 2004 -- The Coalition Provisional Authority, led by L. Paul Bremer, officially transfers "sovereignty" of Iraq to an Iraqi judge. Hours later, Prime Minister Iyad Allawi is sworn in.

Jan. 30, 2005 -- Transitional National Assembly elections are held. Proud Iraqis show their purple ink-dipped fingers as a sign they participated in the election.

Aug. 31, 2005 -- Nearly 1,000 people killed in a stampede at a Shiite ceremony in Baghdad.

Oct. 15, 2005 -- Iraqi constitution ratified.

Oct. 19, 2005 -- Saddam Hussein's trial begins. He's accused of war crimes against humanity for the ordered killings of 143 Shiites in Dujail in 1982.

Dec. 15, 2005 -- General elections are held to elect a permanent government and Iraqi National Assembly.

Feb. 22, 2006 -- In Samarra, the Al Aksari Mosque, with its famous golden dome, is blown up by Sunni insurgents. It was one of the holiest sites for Shiite Muslims.

June 7, 2006 -- Abu Musab al-Zarqawi, the leader of Al Qaeda in Iraq, is killed during a U.S. air strike.

Nov. 8, 2006 -- Secretary of Defense Donald Rumsfeld resigns.

Dec. 30, 2006 -- Saddam Hussein is executed by hanging after being found guilty of crimes against humanity.

Jan. 10, 2007 -- President Bush addresses the nation, saying the situation in Iraq is unacceptable, and announces the "troop surge."