Book excerpt: FOR the third time in as many decades America is leading a powerful coalition to war in the Middle East. On September 23rd the offensive expanded dramatically as coalition aircraft and missiles struck in Syria, widening the theatre beyond its initial arena in Iraq. Their target is a radical jihadist group that has grabbed headlines since June, when its black-clad gunmen burst beyond territory they had captured during Syria's civil war and seized big chunks of Iraq, including the country's second biggest city, Mosul. Alarm has grown as they have massacred hundreds of prisoners, sometimes with grisly televised beheadings, and hounded thousands of Christians and other minorities from their homes. Nearly everyone shares a desire to destroy this scourge, yet they cannot seem to agree on what to call it. The group has been variously dubbed ISIS, ISIL, IS, SIC and Da'ish. Why the alphabet soup?