If the Greeks invented a national style of fighting (according to Herodotus), which the French followed (with élan and martial virtues), and the British deviated from (with the indirect approach), whatever happened to the idea that democracies favour defence over offence? That question, posed by Professor Beatrice Heuser of Glasgow University, starts a fast-paced conversation with Peter Roberts that culminates in a rejoinder that a good peace treaty does not necessarily make for a good peace.