Trained fighters there were, but they had the function of frontier defense; when civil war broke out behind them, the imperial governments frequently called back the frontier forces together with the barbarians they had been fighting. At least two great dynasties, the T'ang and the Ming, were destroyed because they used the nomads of the northern wilds in order to put down domestic insurrections. Light cavalry supplemented enormous bodies of infantry. In fact, the Chinese were put down by foreign conquerors only when the foreigners had Chinese allies, or when a campaign of terror had broken the spirit of popular resistance. Chinese warfare showed the disadvantages as well as the advantages of being carried on by what were in effect militia forces. The cruelty was personal and direct, and not covered with fine disclaimers; restraint of armed forces was the distinguished exception rather than the rule. The line between soldier and peasant was one which could be crossed easily, and the line between soldiery and banditry a matter of intention. At its best, military technique was honest and robustly egalitarian; at its worst it led to abuse of force such as lynching, robbery, and fanatical turbulence. The formal records of Chinese dynasties show the use of trained armies in foreign expeditions, in some of which they achieved feats of military accomplishment which rank with any of world history. Domestic troops were also employed as guards and ornamental bodies attached to the throne and other great offices of the Empire. The convenience of rebellion was such as to make revolt a part of the unwritten constitutional practice--that broad ideological framework upon which the Chinese world rested. It was sanctioned by the classics. It served as a barometer of popular opinion. An unsuccessful rebellion, one without the dimmest chance of success, might well be launched by intelligent and patriotic men because its very appearance could prompt the government to reform. In the words of one of the earliest Western writers on the subject: A military and police is maintained sufficient to crush merely factious risings, but totally inadequate, both in numbers and in nature, to put down a disgusted and indignant people. But though no despotism, this same government is in form and machinery a pure autocracy. In his district the magistrate is absolute; in his province, the governor; in the empire, the Emperor. The Chinese people have no right of legislation, they have no right of self-taxation, they have not the power of voting out their rulers or of limiting or stopping supplies. _They have therefore the right of rebellion._ Rebellion is in China the old, often exercised, legitimate, and constitutional means of stopping arbitrary and vicious legislation and administration.[9]