Some Iraqi troops aren't willing to fight for their government. But many Shiites appear willing to fight for their religious leaders.
Afghanistan and Iraq were lumped together in what was called a 'global war on terrorism.'
The United States encouraged Iraqis to rise up after Saddam Hussein's army was driven out of Kuwait. Washington assumed Saddam was weak after losing the 1991 Gulf War. Iraqis rose up, but Saddam's troops killed thousands - Iraqis say tens of thousands - in a counter-offensive.
Iraq was home of the Abbasid Caliphate, a golden age when the Muslim world was at the forefront of math, science and medicine.
On one level, bombing ISIS is easy. The U.S. knows where the group operates. There's no need for a ten-year hunt like the one for Osama bin Laden. The terror group has two capital cities: Mosul in Iraq and Raqqa in Syria. Al-Qaeda never had such an obvious home address.
For many foreign fighters, the jihad in Iraq and Syria is a commuter war.
The truth was, there was never a connection between Iraq and Osama Bin Laden. There were no weapons of mass destruction, either.
The Iraqi government will try and retake some of the cities have that been captured by ISIS. That means the Shiite government dropping bombs on civilian areas, on Sunni cities. There will likely be a response with car bombings here in Baghdad, and this could be a long fight.
A lot of Iran's empowerment is a result of the war in Iraq.
The Syrian border town of Qa'im was the main gateway Islamic radicals used to go to Iraq. Syria became the passageway for extremists from Egypt, Libya, Afghanistan, Yemen, Saudi Arabia and other Muslim nations to fight a jihad against American forces in Iraq.
The U.S. spent years and years and billions of dollars to build the Iraqi army only to watch it collapse and hand over so many of its weapons.
The U.S. spent billions of dollars to build a secular, professional national Iraqi army but failed because, despite all the U.S.-supplied guns, tanks and planes, the Iraqi military fell apart when challenged by a band of terrorists.
The U.S. presence and American missteps made ethnic violence in Iraq far worse than it would have been otherwise after Saddam Saddam Hussein's fall.
Women, who enjoyed a high social status and levels of education under Saddam, saw terrible setbacks as Iraq fell into civil war. As a result of the sectarian violence from 2005-2007, women retreated to their homes and fell from public view.
Initially, before the modern state of Iraq was created, there were three separate provinces here: a Shiite in the south, a largely Sunni one in the middle, and a Kurdish one in the north.
In October 2008, American commandos launched a cross-border raid into Syria to capture an Islamic militant known as Abu Ghadiya. He was accused of being one of al Qaeda in Iraq's main smugglers of fighters and money between Iraq and Syria.