In 2014, ISIS launched an offensive in Iraq taking control of about a third of Iraqi territory including the second-biggest city, Mosul.
The war to reclaim the territory was long and brutal with liberation efforts in each town and city met with fierce resistance.
Military support to Iraqi forces from the US, Canada and other European allies was also bolstered by Russian logistical and military aid.
On December 9th 2017, Prime Minister Haider al-Abadi declared final victory over ISIS after Iraqi forces drove its last remnants from the country.
Abadi declared December 10th as a national holiday to be celebrated every year to mark the victory.
Following the defeat, ISIS has switched to an insurgency campaign in Iraq using guerrilla tactics
Victory Day is marked by a military parade and state television airing celebratory songs praising government forces.