Interventions in other states on behalf of their subject populations is often portrayed as a novel phenomenon in state practice, one which breaches the old principle of sovereignty. But is this practice really so new? Patrick Milton argues that such interventions for the protection of other rulers' subjects occurred frequently as far back as the sixteenth, seventeenth, and eighteenth centuries. It is the first detailed study of interventions in the early modern period and focusses on centr...

It was the original forever war, which went on interminably, fuelled by religious fanaticism, personal ambition, fear of hegemony, and communal suspicion. It dragged in all the neighbouring powers. It was punctuated by repeated failed ceasefires. It inflicted suffering beyond belief and generated waves of refugees. No, this is not Syria today, but the Thirty Years' War (1618-48), which turned Germany and much of central Europe into a disaster zone. The Thirty Years' War is often cited as a...