More than 50,000 Iraqi soldiers, Kurdish Peshmerga fighters, Sunni Arab tribesmen and Shia militiamen are engaged in a bloody battle to re-take control of Mosul from IS.
In June 2014, IS took control of Mosul, Iraq’s second largest city after Baghdad.
The loss was a humiliation for the Iraqi army and a shocking show of strength from the Islamist terror group which stunned the world with the strength of its advance from Syria into Iraq.
Backed by US-led coalition air support the Iraqi forces have more fighters and more sophisticated weaponry than IS, but the campaign is still expected to take weeks, if not months.
Rights groups are urging both sides to respect international law to minimise civilian deaths and revenge attacks and aid groups are warning of a humanitarian catastrophe.