these were actually built for military purposes.

The state of Ch'in had never been so closely associated with the feudal
communities of the rest of China as the other feudal states. A great
part of its population, including the ruling class, was not purely
Chinese but contained an admixture of Turks and Tibetans. The other
Chinese even called Ch'in a "barbarian state", and the foreign influence
was, indeed, unceasing. This was a favourable soil for the overcoming of
feudalism, and the process was furthered by the factors mentioned in the
preceding chapter, which were leading to a change in the social
structure of China. Especially the recruitment of the whole population,
including the peasantry, for war was entirely in the interest of the
influential nomad fighting peoples within the state. About 250 B.C.,
Ch'in was not only one of the economically strongest among the feudal
states, but had already made an end of its own feudal system.

Every feudal system harbours some seeds of a bureaucratic system of
administration: feudal lords have their personal servants who are not
recruited from the nobility, but who by their easy access to the lord
can easily gain importance. They may, for instance, be put in charge of
estates, workshops, and other properties of the lord and thus acquire
experience in administration and an efficiency which are obviously of
advantage to the lord. When Chinese lords of the preceding period, with
the help of their sub-lords of the nobility, made wars, they tended to
put the newly-conquered areas not into the hands of newly-enfeoffed
noblemen, but to keep them as their property and to put their
administration into the hands of efficient servants; these were the
first bureaucratic officials. Thus, in the course of the later Chou
period, a bureaucratic system of administration had begun to develop,
and terms like "district" or "prefecture" began to appear, indicating