So why do governments initiate such campaigns of extreme violence? What drives seemingly rational, ordinary members of society to participate in them, committing brutal acts and unspeakable atrocities against those they would otherwise call colleagues, neighbours and even friends?

In his new book, Ideology and Mass Killing: The Radicalized Security Politics of Genocides and Deadly Atrocities, Dr Jonathan Leader Maynard, a lecturer in international politics at King’s College London, sets out to answer these questions. Focusing on ideology’s role in explaining the complex phenomenon of atrocity, he looks in detail at how narratives justifying the violence are created, how coalitions of participants are built, and how ideology shapes the character of the killing.

Analysing atrocities committed under Josef Stalin, Allied area bombings in the Second World War, mass killing in Guatemala’s civil war, and the Rwandan genocide, Dr Leader Maynard takes a closer look at the factors that link some of history’s worst cases and the essential role of ideology within them.

Dr Leader Maynard explains: “Contrary to conventional wisdom, mass killings are not primarily rooted in strange ideological plans to transform whole societies, but nor are they simply ‘unideological’ forms of ruthless realpolitik that people employ brutally, but essentially ‘rationally’.

“With very few exceptions, mass killings are security-centric strategies – aimed at defeating perceived enemies, upholding regimes, policing societies, and winning wars – but strategies vitally guided by certain kinds of radical ‘hardline’ ideologies.

“These sorts of ‘hardline’ ideologies are not, as is commonly thought, generally built on hateful or revolutionary values or goals that are unlike those of ordinary, decent, civilized societies. Instead, such ideologies rest on radicalised interpretations of quite familiar ideas about security, self-defence, punishment, duty, warfare, and order. When embedded in extreme ideological narratives of threat and militarism, these ‘ordinary’ ideas allow large-scale violence against civilians to appear strategically and morally justifiable in times of crisis.

“Recognising this allows us to better anticipate atrocities, to understand their social origins and the mentality of their perpetrators, and to reduce the risks of such violence in the future.”

The book, published by Oxford University Press, is available from 28 June. Find out more here.