Intermittent bitter winters result in negative real interest rates - you'd gladly give up a loaf of bread plus something else now (in summer) for a guaranteed l

Intermittent bitter winters result in negative real interest rates - you'd gladly give up a loaf of bread plus something else now (in summer) for a guaranteed loaf of bread later (in winter). With periodic long-term negative real interest rates, hoarding or investing in hoard-protecting projects (fortresses, larders, giant walls) makes more sense than investing in capital that will become idle in a long-term bitter winter - especially when that source of capital makes you a target.