Last week we read that Isis was crumbling, but still a force to be reckoned with. That is true, but its army is by definition a mercenary one, fighting for pay, and when that runs out, so will they. Ancient Greeks knew all about mercenaries.

The 6th century bc Cretan mercenary Hybrias proclaimed ‘I have great wealth — a spear, a sword and a fine shield to save my skin.