On March 19, 2003, the United States began a military operation in Iraq. The U.S. government believed that Iraq's leader, Saddam Hussein, had dangerous weapons. They also believed he was a threat to other countries in the region. President George W. Bush gave the order to begin the attack. Missiles and bombs struck the capital city of Baghdad that night. American soldiers, along with troops from Britain and other allied countries, moved into Iraq from the south. Within weeks, Saddam Hussein's government fell. However, the war was far from over. Fighting continued for many years after that. The decision to go to war was controversial. Millions of people around the world held protests before the war even started. Some of the largest marches in history took place in cities like London, Rome, and New York. People disagreed about whether the war was necessary or right. The Iraq War lasted until 2011 and changed the lives of millions of people.