For most of its history, Europe has been a particularly bellicose continent. Throughout much of that history, however, Europeans have also been concerned to the point of obsession with not merely how to limit the damage inflicted by war but also how to eliminate warfare altogether. This is the story Stella Ghervas has to tell in her remarkable new book. It is a long and complex one, narrated with great skill and passion. She describes it as ‘a theatrical dialogue in five acts’, each act being inspired by what she calls a ‘spirit of peace’.

The first of these began in 1713, with the appearance of a long treatise entitled A Project for Establishing a Perpetual Peace in Europe, written by an otherwise obscure French diplomat, the abbé de Saint-Pierre. It was just one among many such projects, but together with Immanuel Kant’s far more ambitious Perpetual Peace of 1795, which sought to bring peace not just to Europe but to all humanity, it was the most influential of them. It envisaged a future European federation drawn together through the beneficial effects of trade, bound by a ‘Treaty of European Union’ and ruled by a council on which the princes of each of the member states would sit. All the disputes that arose across the continent would be resolved by this council without threatening the sovereignty of any one of the member states. All that was required, in Saint-Pierre’s imagination, to bring together the warring sovereigns of Europe was a single act of collective will. The Project may have been, as Voltaire said of it, ‘a chimera which could no more exist among princes than it could among elephants and rhinoceroses, or wolves and dogs’, but it laid out what was to remain the objective of most of those seeking ‘perpetual peace’ within Europe until the end of the Second World War.

Ghervas’s second act began in 1814–15 when, with the final destruction of the Napoleonic empire, the great powers of Europe (Britain, Russia, Austria and Prussia) gathered in Vienna to create what they called the ‘Concert of Europe’: an open-ended series of conferences to be held at regular intervals