Insurgencies have been around for thousands of years, going back to at least Roman times. A look at history tells us that, far more often than not, insurgents have succeeded in wearing down a far stronger adversary.

So what makes a counter-insurgency strategy successful? David Kilcullen is the latest in a long line of historians and strategists who have answered that question. He is the author of The Accidental Guerrilla: Fighting Small Wars in the Midst of a Big One and a more general book called Counterinsurgency. He has advised the Australian and the American governments, and worked closely with General David Petraeus to revise the US army’s manual on counter-insurgency.

In both these books, David tells us that counter-insurgency is a race against time and victory goes to states who adapt most quickly. Those who win isolate insurgents from their supporters and win their loyalty by protecting the populations at risk. The objective is not to kill insurgents, but to win over the people so they cut off the oxygen insurgents need to survive.

David has written a new book, Blood Year: The Unraveling of Western Counterterrorism. As he tells DTGO host Janice Stein, it is a confession of failure; that he got it wrong in his earlier two books.