If you like neat lines, tidiness and admire symmetry, what’s not to like about the decision of Joe Biden to pull American combat troops out of Afghanistan by 11 September 2021 — exactly 20 years on from 9/11? In modern day America it often feels that all roads lead back to 9/11; the single most defining — and scarring — event since Pearl Harbor: the surprise attack by the Japanese on America’s Pacific fleet, which would ultimately bring America into World War Two. And so it was that 9/11 led to this country’s longest military encounter. The attack on the Twin Towers, the plane that flew into the Pentagon, and the one that crashed into a field in Shanksville, Pennsylvania, were initially the spur for a surge of US nationalism. Young people — in fact people of all ages — were going along to armed forces recruitment offices wanting to sign up. America had come under attack; these patriots wanted to fight to defend the country the “land of the free”, and seek revenge on those who would do the US harm.