It is three years since then Iraqi Prime Minister Haider Al Abadi declared the gruelling battle against the most feared terror group in history was over. ISIS had been defeated.

The conflict itself took three long years. The legacy left behind in the rubble of Mosul, the mass graves across Sinjar and the divided parliament in Baghdad will last a generation.

In this week's Beyond the Headlines, host James Haines Young looks back at the time when the black flag of ISIS hung like a pall over Iraq and how its former rule has left a seemingly indelible mark on the country.