He addressed the Emperor as "the ruler of a small country," and advised the Japanese sovereign to pay him tribute at once... or else. The Khan's emissaries returned from Japan without an answer.
Five times over the next six years, Kublai Khan sent his messengers; the Japanese shogun would not allow them even to land on Honshu, the main island.
In 1271, Kublai Khan defeated the Song Dynasty, and declared himself the first emperor of China's Yuan Dynasty. A grandson of Genghis Khan, he ruled over much of China plus Mongolia and Korea; meanwhile, his uncles and cousins controlled an empire that stretched from Hungary in the west to the Pacific coast of Siberia in the east. The great khans of the Mongol Empire did not tolerate impudence from their neighbors.
As early as 1272, Kublai Khan wanted to launch a strike against Japan. His counselors advised him to bide his time until a proper armada of war ships could be built.
The Mongols commissioned the construction of 300 to 600 vessels from the shipyards of southern China and Korea, and conscripted an army of some 40,000 men. Many of the officers were Mongolian, but the majority of the soldiers were ethnic Chinese and Koreans.
Against this mighty force, Japan could muster only about 10,000 fighting men from the ranks of the often-squabbling samurai clans. Japan's warriors were seriously outmatched.
The First Invasion, 1274
From the port of Masan in southern Korea, the Mongols and their subjects launched a step-wise attack on Japan in the autumn of 1274. Hundreds of large ships, and an even larger number of small boats set out into the Sea of Japan. (The exact number of vessels is unknown; estimates range between 500 and 900.)
First, the invaders seized the islands of Tsushima and Iki, which lay about halfway between the tip of the Korean peninsula and the main islands of Japan. Quickly overcoming desperate resistance from the islands' approximately 300 Japanese residents, the Mongol troops slaughtered them all and sailed on to the east.
On November 18, the Mongol armada reached Hakata Bay, near the present-day city of Fukuoka on the island of Kyushu. Much of our knowledge about the details of this invasion come from a scroll which was commissioned by the samurai Takezaki Suenaga, who fought against the Mongols in both campaigns.
Suenaga relates that the samurai army set out to fight according to their code of bushido; a warrior would step out, announce his name and lineage, and prepare for one-on-one combat with a foe. Unfortunately for the Japanese, the Mongols were not familiar with the code. When a lone samurai stepped forward to challenge them, the Mongols would simply attack him en masse, much like ants swarming a beetle.
To make matters worse for the Japanese, the Yuan forces also used poison-tipped arrows, catapult-launched explosive shells, and a shorter bow that was accurate at twice the range of the samurai's longbows. In addition, the Mongols fought in units, rather than each man for himself. Drumbeats relayed the orders guiding their precisely coordinated attacks. All of this was new to the samurai - often fatally so.
Takezaki Suenaga and the three other warriors from his household were all unhorsed in the fighting, and each sustained serious wounds that day. A late charge by over 100 Japanese reinforcements was all that saved Suenaga and his men. The injured samurai drew back a few miles from the bay for the night, determined to renew their nearly hopeless defense in the morning. As night fell, a driving wind and heavy rain began to lash the coast.
Unbeknownst to the Japanese defenders, the Chinese and Korean sailors on board Kublai Khan's ships were busy persuading the Mongolian generals to let them weigh anchor and head further out to sea. They worried that the strong wind and high surf would drive their ships aground in Hakata Bay.
The Mongols relented, and the great armada sailed out into open waters - straight into the arms of an approaching typhoon.
Two days later, a third of the Yuan ships lay on the bottom of the Pacific, and perhaps 13,000 of Kublai Khan's soldiers and sailors had drowned. The battered survivors limped home, and Japan was spared the Great Khan's dominion... for the time being.