The sad thing about being a historian is that everything sounds so familiar. Something like hearing the same horribly song sung by a hundred cover bands.

Pick up a copy of John Dower's War Without Mercy: Race and Power in the Pacific War, Eric Weitz's A Century of Genocide: Utopias of Race and Nation, Ben Keiman's Blood and Soil: A World History of Genocide and Extermination from Sparta to Darfur, James Waller's Becoming Evil: How Ordinary People Commit Genocide and Mass Killing ... our staunch allies, closest trading partners and brothers in solidarity against Isis committed atrocities within the past century that makes Isis look like a bunch of bumbling amateur assholes by comparison.

The problem isn't that Isis is horrible (they are), the problem is that they're so damned common.