The common people had crossbows for shooting birds or pronged hoes for digging which were efficient even in fighting standing armies; they were also frequently in possession of weapons because they were called up as militia against barbarians. Underlying such military conditions, with their highly important political consequences, there were several surprisingly concrete and simple mechanical considerations. The charioteers had come to an end partly because the chariots were drawn by horses yoked in such a fashion that when the horses pulled hard, they often choked themselves. Other factors are suggested by Dubs: By the time that horses became plentiful, so that cavalry was employed, the crossbow had reached such a state of development that cavalry was shown to be inferior to infantry with crossbows. The medieval European crossbow was hampered by the mechanical weakness of its trigger mechanism--the crossbow was likely to be discharged prematurely by a jar; the Chinese Han crossbow had no such defect and was a powerful weapon. A group of crossbowmen with others in the rear to string crossbows and others to bring cocked bows to the marksmen in the front rank, could shoot down cavalry before they could come near enough to discharge the lighter bows cavalry necessarily carried. Cocked crossbows could be carried around safely and fired when needed. A bolt from a powerful crossbow could pierce any armor. Hence the strong-backed peasant with a crossbow had an advantage over the noble no matter how well the noble was armed or how good horses the latter possessed. The only advantage retained by the noble was that of leadership--tactical skill and command of large bodies of infantry. Cavalry became useful for scouting and pursuit chiefly.[8] The character of military techniques caused Chinese politics to be qualified by rebellion or the fear of rebellion. The difference between a mob and an army became slight. In times of poor government there were rebellions almost yearly. Insurrectionary forces gained momentum overnight; from era to era huge mobs, tens and hundreds of thousands strong, swept away governmental armies and erased corrupt or oppressive dynasties. The process may be described as popular unrest made effective with arms, which professional armies could not resist. The low place of the soldier in society prevented men of genius from organizing a dominant military caste; the professional armies were insufficient to make military government effective. By a crude and brutal democracy of mob and murder the populace of China could destroy dynasties and governments whenever economic, social, or political conditions veered too far beyond the limits of the tolerable.