For the Ch'ien-lung period's many wars of conquest there seem to have been two main reasons. The first was the need for security. The Mongols had to be overthrown because otherwise the homeland of the Manchus was menaced; in order to make sure of the suppression of the eastern Mongols, the western Mongols (Kalmuks) had to be overthrown; to make them harmless, Turkestan and the Ili region had to be conquered; Tibet was needed for the security of Turkestan and Mongolia--and so on. Vast territories, however, were conquered in this process which were of no economic value, and most of which actually cost a great deal of money and brought nothing in. They were conquered simply for security. That advantage had been gained: an aggressor would have to cross great areas of unproductive territory, with difficult conditions for reinforcements, before he could actually reach China. In the second place, the Chinese may actually have noticed the efforts that were being made by the European powers, especially Russia and England, to divide Asia among themselves, and accordingly they made sure of their own good share. 6 _Decline; revolts_ The period of Ch'ien-lung is not only that of the greatest expansion of the Chinese empire, but also that of the greatest prosperity under the Manchu regime. But there began at the same time to be signs of internal decline. If we are to fix a particular year for this, perhaps it should be the year 1774, in which came the first great popular rising, in the province of Shantung. In 1775 there came another popular rising, in Honan--that of the "Society of the White Lotus". This society, which had long existed as a secret organization and had played a part in the Ming epoch, had been reorganized by a man named Liu Sung. Liu Sung was captured and was condemned to penal servitude. His followers, however, regrouped themselves, particularly in the province of Anhui. These risings had been produced, as always, by excessive oppression of the people by the government or the governing class. As, however, the anger of the population was naturally directed also against the idle Manchus of the cities, who lived on their state pensions, did no work, and behaved as a ruling class, the government saw in these movements a nationalist spirit, and took drastic steps against them. The popular leaders now altered their programme, and acclaimed a supposed descendant from the Ming dynasty as the future emperor. Government troops caught the leader of the "White Lotus" agitation, but he succeeded in escaping. In the regions through which the society had spread, there then began a sort of Inquisition, of exceptional ferocity. Six provinces were affected, and in and around the single city of Wuch'ang in four months more than 20,000 people were beheaded. The cost of the rising to the government ran into millions. In answer to this oppression, the popular leaders tightened their organization and marched north-west from the