structural:expansion
2003: Invasion

The first Central Intelligence Agency team entered Iraq on 10 July 2002. This team was composed of members of the CIA's Special Activities Division and was later joined by members of the US military's elite Joint Special Operations Command (JSOC). Together, they prepared for an invasion by conventional forces. These efforts consisted of persuading the commanders of several Iraqi military divisions to surrender rather than oppose the invasion, and identifying all the initial leadership targets during very high risk reconnaissance missions.

Most importantly, their efforts organized the Kurdish Peshmerga to become the northern front of the invasion. Together this force defeated Ansar al-Islam in Iraqi Kurdistan before the invasion and then defeated the Iraqi army in the north. The battle against Ansar al-Islam, known as Operation Viking Hammer, led to the death of a substantial number of militants and the uncovering of a chemical weapons facility at Sargat.

At 5:34 am Baghdad time on 20 March 2003 (9:34 pm, 19 March EST) the surprise military invasion of Iraq began. There was no declaration of war. The 2003 invasion of Iraq was led by US Army General Tommy Franks, under the code-name Operation Iraqi Freedom, the UK code-name Operation Telic, and the Australian code-name Operation Falconer. Coalition forces also cooperated with Kurdish Peshmerga forces in the north. Approximately forty other governments, the " Coalition of the Willing ", participated by providing troops, equipment, services, security, and special forces, with 248,000 soldiers from the United States, 45,000 British soldiers, 2,000 Australian soldiers and 194 Polish soldiers from Special Forces unit GROM sent to Kuwait for the invasion. The invasion force was also supported by Iraqi Kurdish militia troops, estimated to number upwards of 70,000.

According to General Franks, there were eight objectives of the invasion:

"First, ending the regime of Saddam Hussein. Second, to identify, isolate, and eliminate Iraq's weapons of mass destruction. Third, to search for, to capture, and to drive out terrorists from that country. Fourth, to collect such intelligence as we can relate to terrorist networks. Fifth, to collect such intelligence as we can relate to the global network of illicit weapons of mass destruction. Sixth, to end sanctions and to immediately deliver humanitarian support to the displaced and to many needy Iraqi citizens. Seventh, to secure Iraq's oil fields and resources, which belong to the Iraqi people. And last, to help the Iraqi people create conditions for a transition to representative self-government."

The invasion was a quick and decisive operation encountering major resistance, though not what the US, British and other forces expected. The Iraqi regime had prepared to fight both a conventional and irregular, asymmetric warfare at the same time, conceding territory when faced with superior conventional forces, largely armored, but launching smaller-scale attacks in the rear using fighters dressed in civilian and paramilitary clothes.

Coalition troops launched air and amphibious assaults on the al-Faw Peninsula to secure the oil fields there and the important ports, supported by warships of the Royal Navy, Polish Navy, and Royal Australian Navy. The United States Marine Corps ' 15th Marine Expeditionary Unit, attached to 3 Commando Brigade and the Polish Special Forces unit GROM, attacked the port of Umm Qasr, while the British Army 's 16 Air Assault Brigade secured the oil fields in southern Iraq.

The heavy armor of the US 3rd Infantry Division moved westward and then northward through the western desert toward Baghdad, while the 1st Marine Expeditionary Force moved more easterly along Highway 1 through the center of the country, and 1 (UK) Armoured Division moved northward through the eastern marshland. The American 1st Marine Division fought through Nasiriyah in a battle to seize the major road junction. The United States Army 3rd Infantry Division defeated Iraqi forces entrenched in and around Talil Airfield.

With the Nasiriyah and Talil Airfields secured in its rear, the 3rd Infantry Division supported by the 101st Airborne Division continued its attack north toward Najaf and Karbala, but a severe sand storm slowed the coalition advance and there was a halt to consolidate and make sure the supply lines were secure. When they started again they secured the Karbala Gap, a key approach to Baghdad, then secured the bridges over the Euphrates River, and US Army forces poured through the gap on to Baghdad. In the middle of Iraq, the 1st Marine Division fought its way to the eastern side of Baghdad and prepared for the attack to seize the city.

On 9 April, Baghdad fell, ending Saddam's 24‑year rule. US forces seized the deserted Ba'ath Party ministries and, according to some reports later disputed by the Marines on the ground, stage-managed the tearing down of a huge iron statue of Saddam, photos and video of which became symbolic of the event, although later controversial. Allegedly, though not seen in the photos or heard on the videos, shot with a zoom lens, was the chant of the inflamed crowd for Muqtada al-Sadr, the radical Shiite cleric. The abrupt fall of Baghdad was accompanied by a widespread outpouring of gratitude toward the invaders, but also massive civil disorder, including the looting of public and government buildings and drastically increased crime.

According to the Pentagon, 250,000 short tons (230,000 t) (of 650,000 short tons (590,000 t) total) of ordnance was looted, providing a significant source of ammunition for the Iraqi insurgency. The invasion phase concluded when Tikrit, Saddam's home town, fell with little resistance to the US Marines of Task Force Tripoli on 15 April.

In the invasion phase of the war (19 March – 30 April), an estimated 9,200 Iraqi combatants were killed by coalition forces along with an estimated 3,750 non-combatants, i.e. civilians who did not take up arms. Coalition forces reported the death in combat of 139 US military personnel and 33 UK military personnel.