“An army of twenty thousand men, even without camp followers, exceeded the population of most European cities; and when that winding horde of soldiers, with ten to fifteen thousand horses, set out on campaign, it could easily eat up, in a few days, all the food and fodder in the adjacent villages and countryside for many miles around. Such an army could not stay put; it had to move; it had to go on seeking new pastures and more stocks of food.”