this was a simple question, nearly fifteen years into the wars it was still hard to answer. There were a lot of dead terrorists. There were also a lot of new ones. As the war against terrorism had progressed in the years since 2001, it had produced at least this: a huge amount of data. Inside the Pentagon, analysis teams poured over records of phone calls and text messages. They examined maps of personal relations, and studied granular statistics about who had been killed and why and when. All of this information went into targeting computers and databases, and what became more and more apparent with each passing year was that the spread of terrorism after 9/11 looked like nothing so much as the spread of a disease. This was, at first, no great insight. After all, revolutionary ideas, dangerous ideologies or just plain panic often look like epidemics. But what was shocking as you studied the Pentagon numbers was the speed of this infection. Disease epidemics, even the most virulently aggressive ones like Ebola or drug-resistant tuberculosis, move at the pace of human contact; they can be watched and blocked and even quarantined. But the contagions associated with terrorism were warp- driven to a pace well beyond what the soldiers and analysts could match or even fully monitor. “Is our current situation such that ‘the harder we work, the behinder we get?” Rumsfeld asked in 2003.38 To be constantly behind. This was a commander’s nightmare. Among other things it was that sense of never quite catching up that had so seared the new generals in the audience of my speeches. But it seemed to be an inescapable reality. One day a guy in Baghdad would figure out how to make an Explosively Formed Penetrator (EFP) - a sort of pipe bomb that becomes a flying chunk of red-hot steel and can smash through a tank from 100 yards away - and ten days later the same design of projectile would take out an official thousands of miles away in rural Afghanistan, before US troops had had a ch