In September 2004 General David Petraeus – then a senior US commander in Iraq – wrote in the Washington Post that he was optimistic American forces were beginning to turn the corner in what was then an 18-month-old war.

“I see tangible progress,” Gen Petraeus wrote. “Iraqi security elements are being rebuilt from the ground up. The institutions that oversee them are being re-established from the top down. And Iraqi leaders are stepping forward.”