United States military operations were conducted under the codename Operation Iraqi Liberation (OIL). The codename was later changed to Operation Iraqi Freedom, due to the unfortunate acronym. The United Kingdom military operation was named Operation Telic.

Multilateral support

In November 2002, President George W. Bush, visiting Europe for a NATO summit, declared that, "should Iraqi President Saddam Hussein choose not to disarm, the United States will lead a coalition of the willing to disarm him."

Thereafter, the Bush administration briefly used the term Coalition of the Willing to refer to the countries who supported, militarily or verbally, the military action in Iraq and subsequent military presence in post-invasion Iraq since 2003. The original list prepared in March 2003 included 49 members. Of those 49, only six besides the U.S. contributed troops to the invasion force (the United Kingdom, Spain, Australia, Poland, Portugal, and Denmark), 33 provided some number of troops to support the occupation after the invasion was complete. Six members have no military.

Invasion force

Approximately 248,000 soldiers from the United States, 45,000 British soldiers, 2,000 Australian soldiers and 194 Polish soldiers from Special Forces unit GROM were sent to Kuwait for the invasion. The invasion force was also supported by Iraqi Kurdish militia troops, estimated to number upwards of 70,000. In the latter stages of the invasion 620 troops of the Iraqi National Congress opposition group were deployed to southern Iraq.

A U.S. Central Command, Combined Forces Air Component Commander report, indicated that as of April 30, 2003, there were a total of 466,985 U.S. personnel deployed for Operation Iraqi Freedom. This included USAF, 54,955; USAF Reserve, 2,084; Air National Guard, 7,207; USMC, 74,405; USMC Reserve, 9,501; USN, 61,296 (681 are members of the U.S. Coast Guard); USN Reserve, 2,056; and US Army, 233,342; US Army Reserve, 10,683; and Army National Guard, 8,866.

Plans for opening a second front in the north were severely hampered when Turkey refused the use of its territory for such purposes. In response to Turkey's decision, the United States dropped several thousand paratroopers from the 173rd Airborne Brigade into northern Iraq, a number significantly less than the 15,000 strong 4th Mechanized Infantry Division that the U.S. originally planned to use for opening the northern front.

Operation Iraqi Freedom Preparation

CIA Special Activities Division (SAD) Paramilitary teams entered Iraq in July 2002 before the 2003 invasion. Once on the ground they prepared for the subsequent arrival of US military forces. SAD teams then combined with US Army Special Forces to organize the Kurdish Peshmerga. This joint team combined to defeat Ansar al-Islam, an ally of Al Qaida, in a battle in the northeast corner of Iraq. The US side was carried out by Paramilitary Officers from SAD and the Army's 10th Special Forces Group.

SAD teams also conducted high risk special reconnaissance missions behind Iraqi lines to identify senior leadership targets. These missions led to the initial strikes against Saddam Hussein and his key generals. Although the initial strike against Hussein was unsuccessful in killing the dictator, it was successful in effectively ending his ability to command and control his forces. Other strikes against key generals were successful and significantly degraded the command's ability to react to and maneuver against the US-led invasion force coming from the south.

SAD operations officers were also successful in convincing key Iraqi Army officers to surrender their units once the fighting started and/or not to oppose the invasion force. NATO member Turkey refused to allow its territory to be used for the invasion. As a result, the SAD/SOG and US Army Special Forces joint teams and the Kurdish Peshmerga were the entire northern force against government forces during the invasion. Their efforts kept the 5th Corps of the Iraqi army in place to defend against the Kurds rather than their moving to contest the coalition force.

According to General Tommy Franks, April Fool, an American officer working undercover as a diplomat, was approached by an Iraqi intelligence agent. April Fool then sold to the Iraqi false "top secret" invasion plans provided by Franks' team. This decoy deception successfully misled the Iraqi military into deploying major forces in Northern and Western Iraq in anticipation of attacks by way of Turkey or Jordan, which never took place. This greatly reduced the defensive capacity in the rest of Iraq and significantly facilitated the actual attacks via Kuwait and the Persian Gulf in the southeast.

Defending force

The number of personnel in the Iraqi military prior to the war was uncertain, but it was believed to have been poorly equipped. The International Institute for Strategic Studies estimated the Iraqi armed forces to number 538,000 (Iraqi Army 375,000, Iraqi Navy 2,000, Iraqi Air Force 20,000 and air defense 17,000), the paramilitary Fedayeen Saddam 44,000, Republican Guard 80,000 and reserves 650,000.

Another estimate numbers the army and Republican Guard at between 280,000 to 350,000 and 50,000 to 80,000, respectively, and the paramilitary between 20,000 and 40,000. There were an estimated thirteen infantry divisions, ten mechanized and armored divisions, as well as some special forces units. The Iraqi Air Force and Iraqi Navy played a negligible role in the conflict.

During the invasion, Iraqi forces, along with foreign volunteers from Syria, traveled to Iraq and took part in the fighting, usually under the command of the Saddam Fedayeen. It is not known for certain how many foreign fighters fought in Iraq in 2003, however, intelligence officers of the U.S. First Marine Division estimated that 50% of all Iraqi combatants in central Iraq were foreigners.

In addition, the terrorist group Ansar al-Islam controlled a small section of northern Iraq in an area outside of Saddam Hussein's control. Ansar al-Islam had been fighting against Kurdish forces since 2001. At the time of the invasion they fielded approximately 600 to 800 fighters. Ansar al-Islam was led by the Jordanian-born militant Abu Musab al-Zarqawi, who would later become an important leader in the Iraqi insurgency. Ansar al-Islam was driven out of Iraq in late March by a joint American-Kurdish force during Operation Viking Hammer.