The United States-led invasion of the Republic of Iraq was the first stage of the Iraq War. The invasion began on 19 March 2003 and lasted just over one month, including 26 days of major combat operations, in which a combined force of troops from the United States, the United Kingdom, Australia and Poland invaded Iraq. Twenty-two days after the first day of the invasion, the capital city of Baghdad was captured by coalition forces on 9 April after the six-day-long Battle of Baghdad. This early stage of the war formally ended on 1 May when U.S. President George W. Bush declared the "end of major combat operations" in his Mission Accomplished speech, after which the Coalition Provisional Authority (CPA) was established as the first of several successive transitional governments leading up to the first Iraqi parliamentary election in January 2005. U.S. military forces later remained in Iraq until the withdrawal in 2011.

Ba'athist Iraq, officially the Iraqi Republic (1968–1992) and later the Republic of Iraq (1992–2003), was the Iraqi state between 1968 and 2003 under the rule of the Arab Socialist Ba'ath Party. This period began with high economic growth, but ended with the country facing severe levels of socio-political isolation and economic stagnation. By the late 1990s, the average annual income had decreased drastically due to a combination of external and internal factors. UNSC sanctions against Iraq, in particular, were widely criticized for negatively impacting the country's quality of life, prompting the establishment of the Oil-for-Food Programme. The Ba'athist period formally came to an end with the 2003 invasion of Iraq, and the Ba'ath Party has since been indefinitely banned across the country.