- 環日本海研究 (ISSN:13430300)
- no.9, pp.51-59, 2003-10-01
Japan was attacked two times by the Mongols during the Kamakura period; the first was the battle of Bun-ei in 1274 and the second was that of Koan in 1281. It was an article of faith that Japan was the god-blessed land because the Kamikaze, a windstorm raged by God, warded off the Mongolian invaders in these times. Documentary records on the battle of Bun-ei are alternative; some of them was described stories such as the Mongolian troops being caught by a windstorm at the night in Oct. 20 in 1274, or another as they withdrew strategically from Japan. A meteorological study on the probability of a strike of a typhoon at both time of battles is made in this paper. According to the record by the Japan Meteorological Agency, typhoons hardly ever strike the Japanese Islands and a stable weather is continued in the latest autumn such as the time of battle of Bunei. Moreover, a temperate cyclone, which has appeared to the southeastern terrestrial part of China or Eastern China Sea, is still underdeveloped when it has arrived at the northern Kyushu region and it could accompany with not windstorm but much rain. The present provides a key to find a clue of the past and present climatical condition would have unchanged during the last century. It is, consequently, difficult to conclude that the Mongols disappeared from the Hakata bay due to some meteorological phenomenon at the time of battle of Bun-ei. However, it is definite that a big typhoon made land fall on the northern Kyushu region at the time of battle of Koan judging from not only all documentary records but the circumstance estimated meteorologically. Almost of Mongolian battle ships were destroyed and sank into the Sea of Genkai-nada. This typhoon should be considered to move northward along the eastern coast of Kyushu, across Chugoku, and through into Japan Sea at the early morning of Aug.17 in 1281. Due to the strategic imperative of sending 130,000 troops across the Eastern Chine Sea, Momgolians can be considered to have had the requisite knowledge about damage that can be caused by severe weather in the typhoon season. Nevertheless, why they meet a typhoon? No speculation which goes around regarding this problem, of course, is eliminated. It is my opinion that they had no way of knowing the fact that a typhoon season shifted earlier from the late September to the middle August during the latest 13C.