“I’m supposed to be dead,” said Donald Trump, and it’s incredible how close he came. The bullet fired by Thomas Matthew Crooks from a roof in Pennsylvania grazed the former president’s ear. Video suggests he was saved by a head tilt seconds before.

America, warn pundits, was “one inch away from civil war”. Call this distasteful speculation if you wish, but it’s not hyperbolic. It summarises the mood on the ground and the popular memory of past catastrophes.

When people say “civil war”, they don’t mean the 1860s, when North vs South had alternative governments and armies of thousands, but rather the 1960s – when civil unrest was triggered by assassinations and armed extremists lurked in the shadows.

Riots in the wake of the shooting of Martin Luther King Jnr, in April 1968, left 43 dead, 3,500 injured and 27,000 arrested. Liberals demanded reform; conservatives, law and order.

Trump and Biden are old enough to remember those days, and their world-views are shaped by them. Mr Biden sees himself as the heir to Bobby Kennedy, himself assassinated in June 1968. Trump is likened to Richard Nixon.