21st centuries Baghdad remained under Ottoman control until World War I, when on 11 March 1917 it was captured by British forces. After the war, Baghdad was placed under the control of a British Mandate. During the period of British control, the Mandatory administration ordered the construction of several new architectural projects around the city. Iraq was given formal independence by the British in 1932, and increased autonomy in 1946. On 14 July 1958, the Iraqi king, Faisal II, was executed and the monarchy was dissolved after a revolution, forming a republic. The city's population grew from an estimated 145,000 in 1900 to 580,000 in 1950. During the 1970s Baghdad experienced a period of prosperity and growth because of a sharp increase in the price of petroleum, Iraq's main export. New infrastructure including modern sewers, water, and highway facilities were built during this period. However, the Iran–Iraq War of the 1980s was a difficult time for the city, as money flowed into the army and thousands of residents were killed. Iran launched a number of missile attacks against Baghdad, although they caused relatively little damage and few casualties. In 1991 the first Gulf War caused extensive damage to Baghdad's transportation, power, and sanitary infrastructure. Baghdad was bombed heavily in March and April 2003 in the 2003 invasion of Iraq, and fell under US control by April 7–9. Additional damage was caused by the severe looting during the days following the end of the war. With the deposition of Saddam Hussein's regime, the city was occupied by U.S. troops. The Coalition Provisional Authority established a three-square-mile (8 km2) "Green Zone" within the heart of the city from which it governed Iraq during the period before the new Iraqi government was established. The Coalition Provisional Authority ceded power to the interim government at the end of June 2004 and dissolved itself. On September 23, 2003, a Gallup poll indicated that about two-thirds of Baghdad residents said that the removal of the Iraqi leader was worth the hardships they encountered and that they expected a better life in five years' time. As time passed, however, support for the occupation declined dramatically. In April 2004, USA Today reported that a follow-up Gallup poll in Baghdad indicated that "only 13 percent of the people now say the invasion of Iraq was morally justifiable. In the 2003 poll, more than twice that number saw it as