I was listening to David Kilcullen on the C-SPAN After Words podcast, where he was interviewed about his book Counterinsurgency. One interesting concept struck me from the interview which Kilcullen called the Metz Threshold. Kilcullen described it as the amount of time that a country’s population will tolerate their government prosecuting a war. It is based on research conducted by Dr. Steven Metz; hence the name Metz Threshold. Apparently the Metz Threshold for the US is about three years.