A well-thumbed copy of 1066 and All That fixed some matters in my memory more firmly than the rather less frequented pages of Oman. Guido Morselli’s Past Conditional may turn the history of the First World War inside out but it does it instructively. Imposing a deeply satisfying fiction on acutely unhappy facts, he alters the course of events to demonstrate what would have been logical and likely, and a great deal better for everybody.

When an Austrian officer happens upon a disused goldmine in the Alps, he discovers an elderly local who had worked on it as a young man in the last century, and who explains that it had begun life as the start of an abortive tunnel through the Alps to Italy. The seed sown in that officer’s mind has its harvest in the ‘Edelweiss Expedition’: Morselli has the Austrians orchestrate a surprise eruption through the mountains, followed by a sweeping movement to encircle the Italians from behind, executed vivace assai in perfect harmony and with startling bravura. So swift and smooth is this manoeuvre that all the brutish accompaniments of war – fear and violence and bloodshed – are simply unnecessary. The fait accompli is a bloodless weapon and invariably the best, saving time and energy.

‘Leap the biggest hurdle while we still have momentum’. In the author’s version of history similar tactics are repeated in the other theatres of the war. Stunning inventiveness and superb planning make it possible for ‘invisible skiers clad in ghostly white’ to lure away a French battalion guarding their frontier,