War began as Homo sapiens started to organise into groups.
As societies have changed and technologies have developed, we have fought wars differently, often over greater distances and for longer. In turn, war has brought huge changes to society, for better and worse. Economies, science, technology, medicine, culture: all are instrumental to war and have been shaped by it. Best-selling author Margaret MacMillan FBA CC CH is Emeritus Professor of International History, University of Oxford and Professor of History, University of Toronto and was 2018 Reith Lecturer.