Islamic State of Iraq

The Islamic State of Iraq was a Sunni jihadist insurgent group in Iraq that sought to establish an Islamic state in the Sunni-majority areas of Iraq. The Islamic State of Iraq was led by Abu Ayyub al-Masri and Abu Omar al-Baghdadi from its 15 October 2006 foundation until their deaths in 2010 in a United States raid during the Iraq War. The Islamic State of Iraq consisted mostly of al-Qaeda tribal insurgents resisting the USA, Coalition, and government forces, but it was also composed of former Ba'athist officers from the era of Saddam Hussein that sought to regain power. By 2011, al-Qaeda had been decimated, and the Islamic State of Iraq was on its last legs while it was camped in the western desert of Iraq. Its leader Abu Dua, later known as Abu Bakr al-Baghdadi, united the group with Syrian jihadist groups to form the Islamic State of Iraq and Syria in 2013, exploiting the Syrian Civil War to send cadres to Syria to operate and recruit among the Sunnis in Syria that were also opposed to a sectarian Shia government. ISI's base was Mosul, and it had operations in Baghdad Governorate, Anbar Governorate, and Diyala Governorate, and Baqubah was their proclaimed capital. By 2012, it had around 2,500 fighters, but ISIS would grow to have 100,000.

In 2014, Islamic State's leader Abu Bakr al-Baghdadi rejected Al-Qaeda's authority and declared a caliphate.

He later split his group from Al-Qaeda and renamed his group "Islamic State of Iraq and Syria".

In 2015, Al-Qaeda's decassed leader Ayman al-Zawahiri declared war on ISIS.