The Invasion was led by United States Army and U.S. Marine forces, supported by M1 Abrams tanks, Bradley Fighting Vehicles and M113 tracked armored fighting vehicles. The invasion of the city commenced three days after Allied forces had secured the Baghdad airport.
U.S. officials said that their forces fought skirmishes there with Iraq's Special Republican Guard, with two task forces going up to the Tigris river from the southern outskirts of the city before moving west towards the airport. Major General Victor Renuart said the intention was to indicate to the Iraqi leader that coalition forces could move in and out of Baghdad whenever they wished. The Guardian reported that U.S. forces occupied two "presidential palaces". The Army also surrounded the Information Ministry and other key government installations for a while.
On April 4, American troops seized the city's airport on the southwestern edge of the city. The day after, the U.S. sent limited tank raids into the heart of Baghdad. Here American soldiers battled Iraqi forces in heavy street fights. On April 7, U.S. troops took control of a major presidential palace along the Tigris river. American commanders on the ground said that they would remain in the city center rather than retreat to the outskirts as they had done previously.
Iraq, which had no free press, initially issued a statement contradicting Western reporters' accounts of the invasion. Muhammed Saeed al-Sahaf, head of the Information Ministry, told a press conference on April 7 that there were no US troops in Baghdad, saying: "Their infidels are committing suicide by the hundreds on the gates of Baghdad. Be assured, Baghdad is safe, protected. Iraqis are heroes."
Western news media reported the denial as straight news, while continuing to report Allied military activity within Baghdad, such as the capture of two of Saddam's presidential palaces. The denials tapered off after U.S. military forces surrounded the Information Ministry. For more information on the evacuation and disbandment of the Iraqi Government see Saddam Hussein.
As the American forces secured control of the capital, Iraqi civilians immediately began looting the palaces, as well as government offices. Before a conglomerate of international press (and small crowd of around 100 U.S.-supported Iraqi militia  ), a 20-foot tall statue of Saddam in Firdus Square was toppled by an American armored recovery vehicle. Initially, a Marine corporal named Edward Chin of the 3rd Battalion, 4th Marines Regiment placed a United States flag on the statue's head, though it was replaced with an Iraq flag. Various other symbols of the president's personality cult were defaced.
As the U.S. forces were occupying the Republican Palace and other central landmarks and ministries on April 9, Saddam Hussein had emerged from his command bunker beneath the Al A'Zamiyah district of northern Baghdad, and greeted excited members of the local public. This impromptu walkabout was probably his last and his reasons for doing so are still unclear. It is possible that he wished to take what he thought might be his last opportunity to greet his people as their president. The walkabout was captured on film and broadcast several days after the event on Al-Arabia Television and was also witnessed by ordinary people who corroborated the date afterwards. He was accompanied by bodyguards and other loyal supporters including at least one of his sons and his personal secretary. After the walkabout Hussein returned to his bunker and made preparations for his family.
The Americans had meanwhile started receiving rumors that Saddam was in Al A'Zamiyah and at dawn on April 10th, they dispatched three companies of US Marines to capture him. U.S. Marines fought a fierce four-hour battle at a Baghdad mosque where senior Iraqi leaders had been thought to be holed up, as US warplanes attacked areas of the city under the control of Arab fighters. "We had information that a group of regime leadership was attempting to organize...a meeting. The fighting in and around the mosque complex could not be avoided as enemy forces were firing from the area of the mosque." said Captain Frank Thorp. Marines came under fire from rocket-propelled grenades, mortars and Kalashnikov assault rifles. One American Marine was killed and more than 20 were wounded, but neither Saddam nor any of his aides were found. Non-Iraqi Arab volunteer fighters were in control of several streets in the Aadhamiya district, where the mosque is located, and also in the nearby Waziriya district. Arab fighters were also out in force on the streets of the Mansur district west of the Tigris river, close to the Iraqi intelligence service headquarters. US planes swooped overhead, hitting targets in areas under Arab control. In the northeast of the capital, US Marines swept through the Saddam City district in the early hours, blasting forces still loyal to Saddam with heavy artillery, mortar and machine-gun fire. Planes buzzed the area in support of the marine units and soldiers reported seeing Iraqi anti-aircraft fire arching up into the night sky against the noisy but invisible aircraft. The area around Saddam City, home to about two million impoverished Shi'ite Muslims, was the marines' final objective on the eastern flank of the city center.
By late afternoon on April 12 the last shots were fired in resistance to the Americans in Baghdad. One American soldier was killed on the last day of fighting. The battle for Baghdad was over, though insurgent (or resistance) forces continue to operate in Baghdad currently.
In subsequent days, looting and unrest became a serious issue. Iraqis totally plundered the majority of government and public buildings, to the point of there being nothing of any value left. At the important Yarmuk Hospital, not only all beds, but absolutely all its medical equipment, both large and small, was stolen. One other hospital managed to keep on functioning in a manner by organizing local civilians as armed guards.
At the National Museum of Iraq, which had been a virtual repository of treasures from the ancient Mesopotamian cultures as well as early Islamic culture, many of the 170,000 irreplaceable artifacts were either stolen or broken (partially found safe and well later). On April 14, Iraq's National Library and National Archives were burned down, destroying thousands of manuscripts from civilizations dating back as far as 7,000 years.
The damage to the Iraqi civilian infrastructure, economy and cultural inheritance from looting and arson may have been higher than those from three weeks of US bombing. The bombing had been focused on government targets, though civilian areas, such as markets, were destroyed as well.