War is expensive. Mercenaries must be paid, soldiers must be armed, maintained, fed, and equipped. Not only must the war machinery be fed, but at the same time, conscripts often leave behind farms and businesses which lapse in their absence. For this reason, although wars have occurred throughout man's history, wars themselves have generally been as short as possible. It is partly because of the serious cost, not only in lives but also in gold, that many nations have been forced to assess priorities before rushing forward in a military campaign.