Book excerpt: Part of the Small Wars Journal (SWJ) Anthology, Hammer of the Caliphate is a continuation of previous works on the Islamic State, Al-Qaeda, and their affiliate groups. The anthology title is a play on words related to the fifteenth-century treatise Malleus Maleficarum (Hammer of the Witches). Given the Islamic State’s predisposition for engaging in heinous acts and barbaric atrocities in the name of their apocalyptic god, one derived from a perverted version of what mainstream Islam is today, declaring IS anathema to our modern world seems only fitting. The work represents the fifth volume in the SWJ series of radical Islamist-focused anthologies.