“More often geographical expansion is a concomitant of real decline and coincides with a ‘time of troubles’ or a universal state—both of them stages of decline and disintegration. The reason is not far to seek. Times of trouble produce militarism, which is a perversion of the human spirit into channels of mutual destruction, and the most successful militarist becomes, as a rule, the founder of a universal state. Geographical expansion is a by-product of this militarism, in interludes when the mighty men of valour turn aside from their assaults upon their rivals within their own society to deliver assaults upon neighbouring societies.”
Arnold J. Toynbee