Jobbery and corruption were rife; and at the present juncture these agencies were successfully employed to effect the recall of a really able general who had been sent from Peking to recover lost ground, and prevent further encroachments by the Manchus. For a time, Nurhachu had been held in check by his skilful dispositions of troops, Mukden was strongly fortified, and confidence generally was restored; but the fatal policy of the new general rapidly alienated the Chinese inhabitants, and caused them to enter secretly into communication with the Manchus. It was thus that in 1621 Nurhachu was in a position to advance upon Mukden. Encamping within a mile or two of the city, he sent forward a reconnoitring party, which was immediately attacked by the Chinese commandant at the head of a large force. The former fled, and the latter pursued, only to fall into the inevitable ambush; and the Chinese troops, on retiring in their turn, found that the bridge across the moat had been destroyed by traitors in their own camp, so that they were unable to re-enter the city. Thus Mukden fell, the prelude to a series of further victories, one of which was the rout of an army sent to retake Mukden, and the chief of which was the capture of Liao-yang, now remembered in connection with the Russo-Japanese war. In many of these engagements the Manchus, whose chief weapon was the long bow, which they used with deadly effect, found themselves opposed by artillery, the use of which had been taught to the Chinese by Adam Schaal, the Jesuit father. The supply of powder, however, had a way of running short, and at once the pronounced superiority of the Manchu archers prevailed. Other cities now began to tender a voluntary submission, and many Chinese took to shaving the head and wearing the queue, in acknowledgment of their allegiance to the Manchus. All, however, was not yet over, for the growing Manchu power was still subjected to frequent attacks from Chinese arms in directions as far as possible removed from points where Manchu troops were concentrated. Meanwhile Nurhachu gradually extended his borders eastward, until in 1625, the year in which he placed his capital at Mukden, his frontiers reached to the sea on the east and to the river Amur on the north, the important city of Ning-yüan being almost the only possession remaining to the Chinese beyond the Great Wall. The explanation of this is as follows.