original_query: What major military efforts were taken by Kublai Khan of the Yuan dynasty in 1274 and 1281?
query: What major military efforts were taken by Kublai Khan of the Yuan dynasty in 1274 and 1281 to conquer Japan?
answer: In 1274 and 1281, Kublai Khan launched two major military invasions of the Japanese archipelago.  These attempts, though ultimately unsuccessful, involved large-scale naval expeditions with significant numbers of Mongol, Han Chinese, Jurchen, and Korean troops. The invasions are historically significant for marking the limits of Mongol expansion and representing nation-defining events in Japanese history.