Is there a pattern of wars emerging when economies are in lousy shape?

I recently listened to trends researcher Gerald Celente and Marc Faber (of GloomBoomDoom report fame). Both are afraid the USA may incite or get involved in a war to distract the public from the dismal state of the economy. I do realize the USA is already entrenched in Iraq and the bottomless pit known as Afghanistan. Are there any good books written on the topic of wars emerging from countries with lousy economies?