August 15, 1281 - Kublai Khan's massive Mongol invasion of Japan was thwarted on this day by a typhoon that destroyed the invader's fleet of more than 4000 ships and 140,000 men. Next to D-Day, this was the largest naval invasion force ever assembled.
It was actually Kublai Khan's second attempt at conquering Japan by sea. 7 years earlier he came ashore and hammered the Japanese in a brutal battle that the Mongols were clearly winning. The arrival of a typhoon saved the day for the Japanese as Kublai Khan withdrew to his ships and sailed away.
By the time the Mongols returned, the Japanese had constructed a huge system of walls along their beaches. Kublai Khan sailed around for a couple of months looking for a weak spot in the Japanese defenses. Once again, mother nature came to Japan's rescue and unloaded on the invaders with a powerful typhoon that decimated the Mongol fleet.
The Mongols never returned.
The Japanese refer to the well-timed storm as a kamikaze, or "divine wind." The same name was applied to the suicide attacks that Japanese airmen used during World War II.