secure the loyalty of the submitted states, and submitted vassals sometimes received high positions in the Shang government. Warriors of the Yi (barbarians) to the south were integrated into Shang units due to their archery skills. Although the Shang depended upon the military skills of their nobility, Shang rulers could mobilize the masses of town-dwelling and rural commoners as conscript laborers and soldiers for both campaigns of defense and conquest. Aristocrats and other state rulers were obligated to furnish their local garrisons with all necessary equipment, armor, and armaments. The Shang king maintained a force of about a thousand troops at his capital and would personally lead this force into battle. From the reign of Wu Ding on, the numbers of permanent standing warriors increased and the conscription of zhongren (commoners) which originally played a support role, became much more common and important role in the military as army sizes expanded. However, the warrior clans were still the core of the army. A highly efficient military reporting system spanning hundreds of miles was organised with a network of boats, chariots, runners and horse riders supported by widely scattered state guesthouses and hostels. There was a system of drums and possibly also signal fires to signal enemy attacks. Military planning was already developed, with assessment of enemy strength, strategic options, routes of advance and transport and logistical necessities. Military campaigns were ordered to obtain the submission of neighbouring states, and others were meant to exterminate enemy states. Rudimentary tactics of taking advantageous positions, concentrating forces at key points and achieving surprise through for instance, ambush or reconnaissance, were in use. Archery was highly esteemed, and officials were already assigned to train soldiers in archery. Based on archaeological evidence the reflex bows of the period had the strength to pierce bone. The main hand-to-hand weapons were dagger-axes and battleaxes. Aristocrats and commoners both fought with axe, spear, bow and dagger-axe, except that aristocrats had better quality weapons and more complete armour. Warfare transformed during the Shang period. Aristocrats went from fighting on foot to fighting from chariots, and archery developed due to the introduction of the composite bow. The high levels of requisite training made warfare more socially stratified and gendered. The massive fortifications of cities disappeared in the late Shang period, coinciding with the rise of the chariot. Western Zhou and Spring and Autumn period While chariots had been used in