commanders in the entire history of the world". Military capabilities The two major security threats to Joseon and Ming China at the time were the Jurchen people, who raided along the northern borders, and the wokou, who pillaged the coastal villages and trade ships.Turnbull, Stephen. 2002, p. 9. This defensive stance within an environment of relative peace pushed the Koreans to depend on the strength of their fortresses and warships. With the transmission of gunpowder and firearms technology from China during Goryeo, Korea improved upon the original Chinese firearm designs, the thunder crash bomb, and developed advanced cannon which were used with great efficiency at sea. Even though China was the main source of new military technologies in Asia, Korea was a manufacturing base for both cannon and shipbuilding during this era. Japan, on the other hand, had been in a state of civil war for over a century, which had the result of turning the island nation into a very proficient warlike society. When traders from the Portuguese Empire arrived in Japan and introduced arquebuses and muskets, the Japanese warlords were quick to adapt to this disruptive innovation, producing en masse the tanegashima matchlock. In the ongoing civil strife, the Japanese refined the drills and tactics to make best use of the new weapon, thus giving them a great advantage over the Korean armies. Korean cannon were not adapted for effective use on land, and firearms were of a less advanced design. The small arms carried by Japanese soldiers proved to be particularly effective during land engagements and sieges. This strategic difference in weapons development and implementation contributed to the trend during the war of Japanese dominance on land and Korean dominance at sea. As Japan had been at war since the mid-15th century, Toyotomi Hideyoshi had 500,000 battle-hardened soldiers at his disposal to form a remarkable professional army in Asia for the invasion of Korea. While Japan's chaotic state had left the Koreans with a very low estimate of Japan as a military threat, there was a new sense of unity among the different political factions in Japan, as indicated by the "sword hunt" in 1588 (the confiscation of all weapons from the peasants). Along with the hunt came "The Separation Edict" in 1591, which effectively put an end to all Japanese wokou piracy by prohibiting the daimyōs from supporting the pirates within their fiefs. Ironically, the Koreans