Anything that reminds US voters of 9/11 has serious political implications. Deaths of soldiers in Afghanistan no longer have the impact they once did. But there is something shocking and new about the death of Mr Stevens, the first American ambassador to be killed anywhere in the world since 1979, which will give a jolt to opinion across the world.

The Libyan revolution was never quite as it was portrayed at the time. It is true that its leaders in Benghazi were astute enough from the beginning to play down the role of Islamic militants in the uprising which began on February 2011. In reality, the rebels were always more violent and anarchic than was reported. The truth is that the Arab Spring uprisings, not just in Libya but across the Arab world, drew much of their explosive strength from the combination of very different people and strands of opinion united by hatred of oppressive and corrupt autocracies.