Lord Sumption, retired Supreme court judge and mediaeval historian, in Unherd today

'War is crucial. Until the beginning of the 20th century, the two principal collective activities of mankind were religion and war. The purpose of the state was to serve the second of those things, but usually the first as well. War is at the heart of the experience of societies. It is what created the state, in that war made it necessary for the state to find a way of organising the resources of a country.' 

'Medieval societies had a completely different attitude towards conflict. We regard war today as an unwanted catastrophe that periodically breaks in on us against our wishes. They regarded war as the norm, the normal way of settling international disputes, and quite a few internal disputes.'

'In the 14th century, the English adopted what I can only describe as terrorist tactics to try and batter the French government into submitting to their demands. They conducted huge raids in which they indiscriminately killed large numbers of people and burned whole villages. This is what we would call terrorism. It really wasn’t until the 18th century that war became a battle between organised armed forces. We’re now reverting to an earlier pattern in which at least one side in any war is a disorganised group of people. Hamas is a good example. They’re semi-organised, and their object is indiscriminate violence because they do not have the resources to confront whoever their enemy is with the same sort of weapons. If you are a semi-state, and the underdog, this is how you wage war. England was 100% of a state in the 14th century, and they still waged war that way.'

The interview is here.