Analysis of wars, however, in which strong countries have done this, shows that as a rule, the "strong" country was one which was strong in a military sense only; and that the "weak" country was a country which was weak only militarily, but which was potentially strong in that it was possessed of wealth in land and goods. Most of the great conquests of history were made by such "strong" over such "weak" countries. Such were notably those wars by which Persia, Assyria, Egypt, Greece, Rome, and Spain gained their pre-eminence; and such were the wars by which they later fell. Such were the wars of Ghenghis Khan, Tamerlane, Mahomet, and Napoleon; such were the wars by which most tribes grew to be great nations, and by which as nations they subsequently fell. No greater cause of war has ever existed than a disproportion between countries or tribes of such a character that one was rich and weak, while the other was strong and poor. Nations are much like individuals--and not very good individuals. Highwaymen who are poor and strong organize and drill for the purpose of attacking people who are rich and weak; and while one would shrink from declaring that nations which are poor and strong do the same, it may nevertheless be stated that they have often been accused of doing so, and that some wars are explainable on that ground and on none other. The wars of Cæsar in Gaul and Britain do not seem to fall in this category, and yet they really do; for Rome was poor in Julius Cæsar's day; and while Gaul and Britain were not rich in goods, they were rich in land, and Rome craved land.