is rule into a coherent whole.

Meanwhile war arose with foreign enemies, who appeared on the western
and northern boundaries of the empire. In this quarter the Tartar tribes
of the desert had long been troublesome, and now a great combination of
these warlike nomads, known as the Heung-nou,--perhaps the same as the
Huns who afterwards devastated Europe,--broke into the defenceless
border provinces, plundering and slaughtering wherever they appeared.
Against this dangerous enemy the emperor manifested the same energy
that he had done against his domestic foes. Collecting a great army,
three hundred thousand strong, he marched into their country and
overthrew them in a series of signal victories. In the end those in the
vicinity of China were exterminated, and the others driven to take
refuge in the mountains of Mongolia.

This success was followed by a remarkable performance, one of the most
stupendous in the history of the world. Finding that several of the
northern states of the empire were building lines of fortification along
their northern frontiers for defence against their Tartar enemies, the
emperor conceived the extraordinary project of building a gigantic wall
along the whole northern boundary of China, a great bulwark to extend
from the ocean on the east to the interior extremity of the modern
province of Kan-suh on the west. This work was begun under the direct
supervision of the emperor in 214 B.C., and prosecuted with the
sleepless energy for which he had made himself famous. Tireless as he
was, however, the task was too great for one man to perform, and it was
not completed until after his death.

This extraordinary work, perhaps the greatest ever undertaken by the
hand of man, extends over a length of twelve hundred and fifty-five
miles, the wall itself, if measured throughout its sinuous extent, being
fully fifteen hundred miles in length. Over this vast reach of mountain
and plain it is carried, regardless of hill or vale, but "scaling the
precipices and topping the craggy hills of the country." It is not a
solid mass, but is composed of two retaining walls of brick, built upon
granite foundations, while the space between them is filled with earth
and stones. It is about twenty-five feet wide at base and fifteen at
top, and varies from fifteen to thirty feet in height, with frequent
towers rising above its general level. At the top a pavement of
bricks--now overgrown with grass--forms a surface finis