The Iraq War was a protracted armed conflict that began in 2003 with the United States-led invasion of Iraq that overthrew the government of Saddam Hussein. This conflict continued for much of the next decade as an insurgency emerged to oppose the occupying forces and the post-invasion Iraqi government. The invasion occurred as part of a declared war on international terrorism and its sponsors under President George W. Bush following the September 11, 2001 terrorist attacks.
The invasion began on March 20, 2003, with the United States, joined by several coalition allies including the United Kingdom, with a “shock and awe” bombing campaign. Iraqi forces were quickly overwhelmed as U.S. forces swept through the country. This invasion led to the collapse of the Ba’athist government and the capture of Saddam Hussein as part of Operation Red Dawn in December of that year. However, the power vacuum following Hussein’s demise coupled with the mismanagement led to widespread sectarian violence between the Sunnis and Shias and a lengthy insurgency against United States and other coalition forces. Many violent insurgent groups were then supported by Iran and al-Qaeda in Iraq. The U.S. responded with another troop surge in 2007 and the winding down of U.S. involvement under President Barack Obama before the formal withdrawal of all combat troops from, Iraq by December 2011.