Kublai Khan is known and revered for his civilian and administrative, not his military achievements. Grandson of Genghis Khan, Kublai sought to govern rather than to exploit and devastate the vast domains bequeathed to him by two generations of Mongol conquests. He made the transition from a nomadic conqueror from the steppes to effective ruler of a sedentary society. Ironically, however, his reign witnessed the Mongols’ most remarkable military success, the subjugation of the Southern Sung dynasty of China, and simultaneously their greatest military fiascos, the failed naval expeditions against Japan and Java.