In early 2014, the jihadist group Islamic State of Iraq and the Levant (ISIL or ISIS) captured extensive territory in Western Iraq in the Anbar campaign, while counter-offensives against it were mounted in Syria. Raqqa in Syria became its headquarters. The Wall Street Journal estimated that eight million people lived under its control in the two countries.

In June the group proclaimed a "worldwide caliphate" and shortened its name to just "Islamic State" (IS).

Timeline

January 2014 3 January: ISIL proclaims itself as an Islamic state in Fallujah. After prolonged tensions, the newly formed Army of Mujahedeen, the Free Syrian Army and the Islamic Front launched offensives against ISIL in the Syrian provinces of Aleppo and Idlib. These groups, proclaiming a "second revolution", attacked ISIL in many village areas, attacking up to 80% of those in Idlib and 65% in Aleppo. 4 January: Fallujah was captured by ISIL after several days of fighting which left more than 100 dead. ISIL claimed responsibility for the car-bomb attack on 2 January that killed four people and wounded dozens in the Beirut suburb of Haret Hreik, a town that acts as headquarters to Hezbollah. 6 January: Syrian rebels managed to expel ISIL from the city of Raqqa, ISIL's largest stronghold and the capital of the Raqqa province. 8 January: Islamists of several Syrian rebel brigades expelled most ISIL forces from the city of Aleppo. However, ISIL reinforcements from Deir ez-Zor province managed to retake several neighbourhood of the city of Raqqa. By this date ISIL had captured Al-Karmah, Hīt, Khaldiyah, Haditha and Al Qaim and several smaller towns in Al Anbar Governorate, while fighting raged in Ramadi and Abu Ghraib. By mid-January ISIL fighters had retaken the entire city of Raqqa, while rebels expelled ISIL from the city of Aleppo and the villages west of it. 13 January: Fallujah Dam was taken by pro-government tribes. In the previous week ISIL militants had used the dam to flood area around the city with the waters of the Euphrates which also caused the lowering of water levels in the southern provinces. 16 January: The Iraqi Army and allied Sunni tribes recaptured Saqlawiyah from ISIL. 22 January: Over 50 ISIL militants were killed by Iraqi Air Force strikes in Al Anbar Governorate. 25 January: ISIL announced the creation of its new Lebanese arm, pledging to fight the Shiaa militant group Hezbollah in Lebanon. 29 January: Turkish aircraft near the border fired on an ISIL convoy inside Aleppo province in Syria, killing 11 ISIL fighters and one ISIL emir. 30 January: ISIL fired on border patrol soldiers in Turkey. The Turkish Army retaliated with Panter howitzers and destroyed the ISIL convoy. Iraqi forces and their tribal allies recaptured Albu Farraj and Al-Nasaf near Ramadi. In late January, Haji Bakr, ISIL's then second-in-command, was reported to have been assassinated by Syrian militants. Haji Bakr had previously been head of al-Qaeda's military council and a former military officer in Saddam Hussain's army. They were unaware that they had killed the strategic head of the group calling itself "Islamic State".

February 2014 3 February: al-Qaeda's general command broke off its links with ISIL, reportedly to concentrate the Islamist effort on unseating President Bashar al-Assad. By mid-February, al-Nusra Front had joined the battle in support of rebel forces, and expelled ISIL forces from the Deir ez-Zor province in Syria. 19 February: An ISIL leader, Abd Khaliq Mahedi, surrendered to the Chairman of Sons of Iraq Council, due to disagreement with other ISIL leaders on the killing of Iraqi soldiers and bombing of civilian houses. 23 February: ISIL carried out a suicide attack in Aleppo, killing a commander of Ahrar ash-Sham (Abu Khalid al-Suri) and six other members of the group. 28 February: The pro-government Sunni tribal Sheikh and councilman, Fleih al-Osman, and six of his men were killed by a suicide bomber in Haditha.

March 2014 By March, ISIL forces had fully retreated from Syria's Idlib province after battles against the Syrian rebels. 4 March: ISIL retreated from the Turkey border town of Azaz and nearby villages, choosing instead to consolidate around Raqqa, in anticipation of an escalation of fighting with al-Nusra. 8 March: Iraqi Prime Minister Nouri al-Maliki accused Saudi Arabia and Qatar of openly funding ISIL."Exclusive: Iraq's Maliki accuses Saudi Arabia of supporting 'terrorism'". France 24. 8 March 2014. 15 March: The number of internally displaced persons in Al Anbar Governorate, especially from Fallujah and Ramadi, reached 300,000. The number of people recorded killed by this date was 336, with 1,562 more wounded. 16 March: Iraqi Security Forces recaptured Ramadi and parts of Fallujah. 20 March: In Niğde city in Turkey, three ethnic Albanian members of ISIL opened fire while hijacking a truck, killing one police officer and one gendarmerie officer and wounding five people. Shortly after their arrest, Polis Özel Harekat teams launched a series of operations against ISIL in Istanbul. Two Azerbaijanis were arrested.

April 2014 16 April: ISIL is reported to have killed Abu Muhammad al Ansari, the Al-Nusra Front emir of Idlib province, Syria. The ISIL assassination team killed his wife, his 2 children, and both of his brothers, who were in his house. 27 April: Iraqi helicopters reportedly destroyed an ISIL convoy inside Syria. This may be the first time that Iraqi forces have struck outside their country since the Gulf War.

May 2014 1 May: ISIL carried out a total of seven public killings in the city of Raqqa in northern Syria. Pictures that emerged from the city show how ISIL had been carrying out public crucifixions in areas under its control. In most of these crucifixions, the victims were shot first and their bodies were then displayed, but there were also reports of crucifixions preceding the victims being shot or decapitated. 9–18 May: The Iraqi Army retook 16 villages and towns around Fallujah.

June 2014 In early June, ISIL was reported to have seized control of most of Mosul, the second most populous city in Iraq, a large part of the surrounding Nineveh Governorate, and the city of Fallujah. ISIL also took control of Tikrit, the administrative centre of the Salah ad Din Governorate, with the ultimate goal of capturing Baghdad, the Iraqi capital. ISIL was believed to have only 2,000–3,000 fighters up until the Mosul campaign, but during that campaign, it became evident that this number was a gross underestimate. Also in June, there were reports that a number of Sunni groups in Iraq that were opposed to the predominantly Shia government had joined ISIL, thus bolstering the group's numbers. However, the Kurds—who are mostly Sunnis—were unwilling to be drawn into the conflict, and there were clashes in the area between ISIL and the Kurdish Peshmerga. 5 June: ISIL militants stormed the city of Samarra, Iraq, before being ousted by airstrikes mounted by the Iraqi military. According to army officials, 12 policemen, 80 ISIL militants and several civilians were killed. The Commander of the Nagshabandiya Movement, Khalil al-Hayeeti, was killed in a clash with government forces in Al Anbar Governorate. Abu Abdulrahman al-Bilawi, the chief of the general military council for the Iraqi provinces of the Islamic state, was killed is Mosul by the Iraqi security forces. 6 June: ISIL militants carried out multiple attacks in the city of Mosul, Iraq. 7 June: ISIL militants took over the University of Anbar in Ramadi, Iraq, killed guards and held 1,300 students hostage, before being ousted by the Iraqi military. 8 June: An ISIL bombing in Jalula killed 18 members of the Kurdish security forces. ISIL forces captured Hawija, Zab, Riyadh, Abbasi, Rashad and Yankaja near Kirkuk. 9 June: Mosul fell to ISIL control. The militants seized control of government offices, the airport, and police stations. Militants also looted the Central Bank in Mosul, reportedly absconding with US$429 million. More than 500,000 people fled Mosul to escape ISIL, including 400 Christian families, nearly the entire Christian element of the population of Mosul."Iraq crisis: Islamists force 500,000 to flee Mosul". BBC News. 11 June 2014. Mosul is a strategic city as it is at a crossroad between Syria and Iraq, and poses the threat of ISIL seizing control of oil production. At the same time, hundreds of Christian families fled from the Nineva Plains in face of the ISIL advance. 15 captured Iraqi soldiers were killed while captive by ISIL near Kirkuk. 10 June: ISIL killed 670 Shia inmates of Badush prison in Mosul. The 4th-century Mar Behnam Monastery was seized by ISIL, which forced its monks to leave without taking anything with them. Sixty UN staff were evacuated from Baghdad to Jordan. 11 June: ISIL seized the Turkish consulate in the Iraqi city of Mosul, and kidnapped the head of the diplomatic mission and several staff members. Baiji, Iraq was captured by ISIL forces, except for its surrounded oil refinery. Tikrit also fell to ISIL, which attacked Samarra as well, without succeeding in conquering it. 46 Indian nurses were stranded in Tikrit (they were released and flown back to India at the beginning of July) 12 June: ISIL captured ten towns in Saladin Governorate and routed an Iraqi Border Patrol battalion heading towards Sinjar with 60 trucks. Some of the 4,000–11,000 cadets and soldiers who had been ordered to leave Camp Speicher base were captured by ISIL; of these 1,095–1,700 were killed over the next three days. Human Rights Watch issued a statement about the growing threat to civilians in Iraq. Twelve imams were killed in Mosul for refusing to swear loyalty to ISIL. The imam of the Grand Mosque of Mosul, Muhammad al-Mansuri, was killed for the same reason. ISIL laid siege to the town of Amirli, where 13,000 Turkmen civilians were trapped. 13 June: ISIL captured two towns in Diyala Governorate and several villages around the Hamrin Mountains. Navi Pillay, UN High Commissioner for Human Rights, expressed alarm at reports that ISIL fighters "have been actively seeking out and killing soldiers, police and civilians, whom they perceive as being associated with the government". Kurdish Peshmerga forces occupied the city of Kirkuk, abandoned by the retreating Iraqi Army in face of the ISIL offensive. Kurdish forces also secured Jalula after it had been abandoned by Iraqi Army. 14 June: The Iraqi Army recaptured the town of Al-Mutasim near Samarra. The bodies of 128 Iraqi soldiers and policemen who had been killed in the battle of Mosul were retrieved. 15 June: ISIL militants captured the Iraqi city of Tal Afar, in the province of Nineveh, and its air base—18 ISIL militants, ten civilians and presumably a heavy number of defenders were killed—and also two villages in Adhaim. The Iraqi Air Force claimed to have killed 278 ISIL militants in airstrikes. Iraqi Army retook the town of Ishaqi, where the burned bodies of 12 policemen were found. 16 June: ISIL ambushed a convoy of Shia militia and killed 28–29 Shia volunteers near Samarra. ISIL also captured Saqlawiyah and shot down a helicopter. Iraqi police killed 44 Sunni prisoners before retreating from Baqubah. 17 June: The Iraqi Army recaptured the lost districts of Baqubah. Syrian rebels captured the Al-Qa'im border crossing from Iraqi forces. The bodies of 18 Iraqi soldiers, killed while captive, were found near Samarra. 18 June: ISIL captured three villages in Salaheddin province; 20 civilians were killed during the fighting. 19 June: ISIL captured the Al Muthanna Chemical Weapons Facility near Lake Tharthar. 21 June: After the agreed desertion of 400 Iraqi soldiers, ISIL captured Iraq's largest oil refinery in Baiji. Thousands of Shia militia members from all over Iraq rallied in a show of strength. Clashes between ISIL and allied Sunni militants left 17 dead in Hawija.