The responses of China and Japan to Western Imperialism were similar in several significant respects. Each nation, for centuries, successfully held back Western incursions into their territories and economies. Both China and Japan were ultimately able to maintain this policy of isolationism until the 19th century, when each finally succumbed to external pressures, though to differing degrees.
By the 19th century, both of these mighty Asian nations found their formal policies of isolationism no longer viable, and each were forced to accede to European interests. China was the first to do so, opening up a limited and controlled zone in the province of Canton to Western merchants. There, a special bureaucracy was established to deal with these Westerners and to contain their influence. By 1853, Japan too began opening its ports to Western merchants, particularly after they saw the naval power of the West. In this most basic sense, the responses of the two nations were similar and occupied the same general stretch of history. Each seemed to sense the moment, and react in a manner that suited the situation.
However, Chinese policy ultimately proved too constrictive for European interests and a series of conflicts known collectively as the Opium Wars eventually brought China to its knees. According to Columbia University, this armed showdown with the West left China completely vulnerable to European imperial ambitions. Japan, on the other hand, proved more pliant to the Westerners, yet it also learned and industrialized on its own. This critical difference is what allowed Japan to grow as a world power in the 20th century, whereas China's road towards modernization was more prolonged and difficult. The results of this disparity between nations was most sorely felt in the cataclysmic and uneven matching of the armed forces of the two countries during World War II.