Over the past two years, several books have appeared focusing on Islamic State (IS). These have largely focused on its history, its ideological appeal or its propensity to make use of social media to spread its message of hate. Other publications have examined the subject matter from a military perspective – that of counter-insurgency. In many ways this book, Irregular War: ISIS and The New Threat From The Margins, is quite unique and reflects the author’s own academic background as a professor in peace studies.