All these expeditions, sometimes national, sometimes filibustering, served to drain the resources of Japan, though many impulses to development and higher civilization were thus gained, especially in the earlier centuries. It seemed, until 1877, almost impossible to eradicate from the military mind of Japan the conviction that to surrender Corea was cowardice and a stain on the national honor. But time will show, as it showed centuries ago in England, that the glory and prosperity of the conqueror were increased, not diminished, when Japan relinquished all claim on her continental neighbor and treated her as an equal. The Coreans taught the Japanese the arts of peace, while the Coreans profited from their neighbors to improve in the business of war. We read that, in 316 A.D., a Corean ambassador, bringing the usual tribute, presented to the mikado a shield of iron which he believed to be invulnerable to Japanese arrows. The mikado called on one of his favorite marksmen to practice in the presence of the envoy. The shield was suspended, and the archer, drawing bow, sent a shaft through the iron skin of the buckler to the astonishment of the visitor. In all their battles the Coreans were rarely able to stand in open field before the archers from over the sea, who sent true cloth-yard shafts from their oak and bamboo bows. The paying of tribute to a foreign country is never a pleasant duty to perform, though in times of prosperity and good harvests it is not difficult. In periods of scarcity from bad crops it is well nigh impossible. To insist upon its payment is to provoke rebellion. Instances are indeed given in Japanese history where the conquerors not only remitted the tribute but even sent ship loads of rice and barley to the starving Coreans. When, however, for reasons not deemed sufficient, or out of sheer defiance, their vassals refused to discharge their dues, they again felt the iron hand of Japan in war. During the reign of Yuriaki, the twenty-second mikado (A.D. 457–477), the three states failed to pay tribute. A Japanese army landed in Corea, and conquering Hiaksai, compelled her to return to her duty. The campaign was less successful in Shinra and Korai, for after the Japanese had left the Corean shores the “tribute” was sent only at intervals, and the temper of the half-conquered people was such that other expeditions had to be despatched to inflict chastisement and compel payment.