January 10 - Protests in the city of Amarah because of an unemployment crisis. Police officers and soldiers open fire on demonstrators.
January 15 - The United Nations call direct elections in advance of July impractical, due to continuing disorder and other factors.
January 18 - A suicide bomber blew up a pickup truck packed with 1,000 pounds of explosives outside the headquarters of the US led coalition killing about 20 people and injuring more than 60 - most of them Iraqis.
February 1 - During the Muslim eid, two suicide bombers kill 117 and wound 235 at two Kurdish buildings in the northern Iraqi city of Arbil. The bombers targeted the two offices for Iraq's main secular Kurdish parties packed with well-wishers. Sunni militant group Ansar al-Sunna claimed the attack.
March 2 - In the Ashoura Massacre almost 200 are killed in a series of bomb blasts in Baghdad and Karbala at the climax of the Shi'a festival of Aashurah. A combination of suicide bombers and mortars hit large Shi'ite crowds mourning outside revered shrines in Kerbala and Baghdad's Kadhimiya shrine.
The governing council unanimously approves the country's new interim constitution
U.S. General Tommy Franks reportedly estimated soon after the invasion that there had been 30,000 Iraqi casualties as of April 9, 2003. After this initial estimate he made no further public estimates.
April 2 Al Sadr gives a heated sermon, which leads to the uprising of the Mahdi army.
April 8 The Mahdi army has taken full control in Kut and partial control of Najaf, Karbala and Kufa.
April 9 A civilian fuel convoy operated by private contractors Halliburton and Kellogg, Brown and Root is ambushed en route to Baghdad International Airport. The Mahdi Army is believed to be responsible for the attack. 7 civilians and several US Army Soldiers were killed in the attack. One of the truck drivers and one Soldier are still missing.
April 10 The U.S. forces declare a unilateral cease fire in Fallujah. Although the U.S. forces fight when provoked, they do not move to take more area.
April 16 Kut is retaken by coalition forces, but Najaf, Karabla and Kufa remain under control by Al Sadr.
April 20 12 mortar rounds were fired on Abu Ghraib Prison by insurgents. 22 detainees were killed and 92 wounded. 
April 21 - At least 73 people were killed, including 17 children, along with 94 wounded in Iraq in suicide attacks on police stations in Basra and Az Zubayr.
The U.S. Marines announce it will pull out of Fallujah over a two- or three-week period and hand over control to the Iraqi army.
At least 600 civilians have been killed during the American attack on Falluja
8 U.S. soldiers are killed and 4 wounded in a car bomb attack near Mahmudiyah, south of Baghdad.
April, Palm Island Secret Society is founded, in the finger lakes area of FOB Danger (1st Infantry Division). Forced underground during the combat tour, however met in secrecy for the remainder of their period of the war, and after.
May 17 - A suicide car bomb in Baghdad kills the head of Iraq's Governing Council Abdul-Zahra Othman Mohammad, a prominent Shi'ite politician from Basra also known as Izzedin Salim. More than a dozen others were also killed in the blast at the gates of the fortified Green Zone in Baghdad.
May 28 - Iyad Allawi is chosen as the prime minister for the interim Iraqi government. The handover is scheduled to take place on June 30.
Paul Bremer signs over limited sovereignty to Iraq's interim government, June 28
The new flag of Iraq
June 28 - Two days ahead of schedule, control and sovereignty of Iraq is handed over from the United States to an interim Iraqi government. Allawi becomes the prime minister, and Paul Bremer leaves the country. A slightly modified form of the flag is used.
September 14 - A car bomb near a crowded market and police station in a Shi'ite area of Baghdad kills at least 47 people and wounds 114.
September 30 - Insurgents detonate three car bombs killing 41 people (34 of them children) in the Shi'ite Amil area of southern Baghdad. The blasts, which wounded 139, occurred shortly after U.S. troops had celebrated opening a new sewage system and distributed sweets to children.
October 1 - An early morning coordinated invasion of Samarra by 3,000 US troops and 2,000 Iraqi troops begins. Iraqis take two religious sites by force. Americans claim to have killed as many as 125 insurgents.
October 9 - Major-GeneralTim Cross is appointed the new General Officer Commanding, Theatre Troops, commanding all British forces deployed in the country.
October 10 - Tawhid and Jihad claims responsibility for two car bombs in Baghdad, killing at least 11 people including an American soldier, and wounding at least 16.
October 12 - Germany's defense minister, Peter Struck, indicated that Germany might deploy troops in Iraq if conditions there change. This gesture appears to provide backing for John Kerry, the US Democratic presidential challenger.
October 13 -
A suicide attack and roadside bombings kills six American soldiers.
Brigades of Abu Bakr Al-Sidiq, believed to be linked to al-Zarqawi, release a video via internet showing the beheading of two Iraqis: Fadhel Ibrahim and Firas Imeil, believed to be members of the Iraqi National Intelligence.
September 28 -
U.S. troops swept into the Sunni stronghold of Ramadi and joined Iraqi police and National Guardsmen in raids in Baqouba.
Investigators uncovered more than 100 bodies in a mass grave near the northern Iraqi village of Hatra. The bodies were believed to be Kurds killed during Saddam's crackdown in 1987-1988. The bodies includes those of small children and their mothers with bulletholes in their skulls. 
October 14 -
Two suicide bombers penetrate the highly guarded green zone in Baghdad and detonate bombs in their backpacks. 5 are killed, 4 of them Americans. 20 others are wounded. Tawhid and Jihad, a group connected to al-Zarqawi, claim responsibility. The bombers are reportedly Jordanians. This is the first successful attack in the green zone. AP
The U.S. responds to the suspension of talks with more air, artillery, and ground attacks. AP
October 15 - A platoon in the 343rd Quartermaster Company refuses orders to convoy supplies from Tallil, Iraq to Taji, Iraq, citing safety concerns. They claim that their vehicles were unsafe and that the convoy isn't adequately protected. The Army launches an investigation. AP
October 25 - Nearly 380 tons of conventional high-explosives are found missing from an Iraqi site formerly used by Saddam Hussein for his dismantled atom bomb program, that was never secured by the United States Army. It is reported by MSNBC that the site was looted in April 2003, before coalition troops reached the area. US troops reported at the time that the explosives were missing. MSNBC
December 19 - A suicide car bomb blast in Najaf, 300 metres from the Imam Ali shrine, near crowds of people, kills 52 and wounds at least 140. On the same day, a car bomb exploded in Kerbala, killing 14 and injuring at least 52.
December 21 a huge explosion rocked a US-base in the northern city of Mosul killing 22 people (14 U.S. soldiers, 4 U.S. contractors and 4 Iraqi National guards) and wounding more than 70 people. At first, there were reports of a rocket attack but later it was said to be a suicide bomber. The Ansar al-Sunnah army in Iraq claimed responsibility. It was the deadliest single-attack on Americans (soldiers and civilians) in Iraq since the war ended on May 1, 2003.
December 27 - A suicide car bomber kills at least 13 people outside the offices of the Supreme Council for Islamic Revolution in Iraq (SCIRI), one of the largest Shi'ite parties in Iraq in the upscale Jadiriya area of Baghdad. Its leader Abdel Aziz al-Hakim said it was a failed attempt on his life and blamed the bombing on Sunni militants.