In the early nineteenth century, at height of the Napoleonic Wars, Britain twice inflicted preventive violence on a small and ostensibly neutral European state, Denmark. On the first occasion, in 1801, it did so to break up the League of Armed Neutrality. On the second occasion, in 1807, Britain sought to pre-empt the possible seizure of the Danish fleet by Napoleon. Both operations were controversial at home and abroad, especially the latter, which involved the destruction of parts of the city of Copenhagen and considerable loss of civilian life. After a short setting of the scene in its broader international context, this lecture will look more closely how the British attack on Copenhagen in 1807 was conceived. It will locate the event within contemporary discussions on international law (the ‘low of nations’), in respect to both ius ad belllum and ius in bello. The author will show how these discussions were embedded in the larger framework of the contest between Napoleonic hegemony and those who supported the ‘balance of power’. London argued, self-interestedly but also persuasively, that the defence of the international freedoms of states, and the whole body of the law of nations itself, rested on Britain’s maritime dominance. This notion was furiously resisted by some but grudgingly recognised by others which explains the ambivalence with which many regarded the events at Copenhagen in 1807.

Brendan Simms is Professor of the History of European International Relations and Director of the Forum on Geopolitics at the University of Cambridge. His publications, which have been translated into many languages, European and non-European, include Europe, the struggle for supremacy, 1453 to the present day (Penguin Press, 2013), Britain’s Europe. A thousand years of conflict and cooperation (Penguin Press, 2016) and Hitler. Only the world was enough (Penguin Press, 2019).