This feels like beating a dead horse, but I had to add and make some corrections.
1. Ming, at least not until the end of the war, were never a major factor.
Ming's first batch of troop was only 5,000, and was eventually beaten. As some has pointed out here, the Imjin War was a secondary importance to Ming. In fact, the Ming Emperor was actually suspicious that the Korean Royal Court was in cahoot with Japan all along. An understandable mistake since Ming had gotten into war at all fronts at the time, but still a mistake nonetheless.
When it was obvious that Korea was really in dire need of help, the Emperor's order was not to defeat Japanese, but make a treaty with them, even at an expense of Korea. At one point, a peace treaty which would have yielded half of the Korean pennisula to Japan was drafted between the Chinese and Japanese. It only didn't go through because Hideyoshi also demanded one of Chinese princesses to be sent as his concubine.
The Chinese army didn't fare that well against Japanese, nor did it really try. During the 2nd invasion, when China finally sent the new troops after a long delay, it had gotten an information about Hideyoshi's failing health, and decided to wait till his death. A smart move, no doubt. It is too bad that they not only let Korean populace suffer raids and pillaging by Japanese, very often they themselves were also doing the exactly the same thing.
Ming's navy was even doing less. Chen Lin's fleet joined the war AFTER the famous(?) 13-vs-133 Myeongnyang Battle, and participated in only 2 actual naval battles, one being the Noryang Battle, the last battle of the Imjin War. In fact, Admiral Yi died during the attempt to rescue Chen Lin, who got himself in danger by going in too deep.
So to say that the Ming's military force was a major factor in the Imjin War would be an overstatement .
2. Portugese ships would not have helped Japan greatly in the Imjin War.
The reason Panoksun was so effective during the war was its level bottom. The Korean coasts are riddled with rocks and high tides. The Portugese ships with its round body were excellent in open sea, would have lost their mobility along the Korean coast. Despite their expertise on sailing, the Japanese sailors would have had difficulties balancing such tall ships constantly being hit by high tides in the Korean seas, especially after shooting a barage of cannon fires. No doubt the Portugese ships were superior in size and speed in comparison to Japanese battleships used at the time, but they were still designed to sail a long distance in an open sea. Facing Admiral Yi's Panoksun in high tides with rocks around, the Japanese navy would have been marginally improved by using the Portugese ships.
Also, many people don't seem to realize is that the defeat of Spanish Armada by the British navy happened only 5 years earlier than the Imjin War. The use of cannons in a naval battle was not exactly an old news in Europe, but both the guns and the tactics used at the time were not really superior to Admiral Yi's.
3. Japanese navy also employed cannons.
Not many in this forum seem to realize, but Japanese used cannons too. Their army used cannons as a siege weapon on land, so to think the navy didn't put the two and two together would be an oversight. Japanese battleships were actually equipped with cannons, and some of the guns were imported from Europe and China. The rest was their own version of the imported design. Some of them were even more powerful than the half of Yi's guns.
The problem was, as mentioned as above, that the southern Korean coast was constantly hit by high tides with rocks abound. The smaller Japanese ships could not keep their balance after shooting with such powerful force. Obviously the accuracy suffered, not like the Joseon navy, whose panoksun held its place firmly even after a heavy shooting. Therefore, many times the Japanese naval officers just never bothered with the cannons.
If your idea of the Imjin naval battles were the Joseon ships firing their mighty cannons while the burnt Japanese ships sank, you are mistaken. The military technology at the time, both in East Asia and Europe, was not advanced enough to produce cannonballs exploding after impact. So one or two hit by cannons wouldn't really sink a ship. Only after a repeated hit by flying metal balls, a ship would sustain enough damage to sink. The typical naval battles of the Imjin War were basically how many times the Joseon cannons could hit Japanese fleet before the Japanese bullets could take down Admiral Yi's crew. If it was as easy as people make it sound like, even Won Gyun, that jealous fool who framed Yi, would have succeeded instead of having the entire navy decimated.
4. Long before Admiral Yi, Japanese soldiers were raiding and pillaging Joseon villages.
One guy had an audacity to claim that it was actually Admiral Yi who forced the Japanese army to plunder the Korean popularce. NOT TRUE! One thing to remember is, Japan wasn't really unified before Hideyoshi, and until then their military policy always had been "to the winner goes the spoil." There were so many factions vying for power that the ownership of some regions had been passed around like a hot potato. In case that they could not maintain the newly won region, it was a normal practice to plunder for whatever available as a reward to the soldiers. Wealth, women, you name it.
Naturally, Japanese army followed its long tradition without haste. People were being killed, and cities were burnt. In fact, there were some European merchants present in the Japanese-occupied Busan for the sole purpose of slave trading. Besides, the Japanese army could survive the first winter in Korea thanks to the Korean provisions abandoned by the Korean King as he fled to north. They didn't pillage because they had to. They did it because that was how they executed a war. Things were going so badly for Koreans that even the Buddist monks grabbed weapons to fight Japanese. The Buddist monks!!
5. Admiral Yi, although he was the Supreme Naval Commander, did not have command of Joseon's entire navy.
A common mistake, even by Koreans. Joseon was divided into 8 provinces, each with its own provincial navy, usually split into two sections. The most southern provinces, Kyungsang and Cholla(Yi's original location), had the bigger navy, while the other 5 only had a handful of battleships. Admiral Yi, at his highest position, was given command of the only three, Kyungsang, Cholla, and Chungcheong.
Of all three, the Kyungsang navy, which was the biggest with over 100 ships, had already been wiped out on the day of invasion. By whom, you ask? Again, that fool Won Gyun, who actually had to burn down all his ships in fear of the Japanese using them. Why, you ask? Because the guy was too drunk to notice the 1000 Japanese ships until they actually reached the harbor. He escaped with only two ships.
Fortunately, the Cholla province, which initially got run over by Japanese army who were in hurry to chase the King, held its own defense of the southern coastal regions thanks to the rise of citizen militias. The same thing for the Chungcheong province, yet neither regions really had enough resources to aid Admiral Yi. Despite his high rank, the only practical command he had was that of Cholla provincial navy.
The other 5 provicial navies, although each of them were not much, all together they could have greatly helped Admiral Yi's effort. Yet the jealous and paranoid King feared that the Japanese might reach him by sea without them guarding him, nor did he want to give Admiral Yi that much power. Unbelievable, but true.
6. Admiral Yi not only had to fend for himself, but had to feed the Royal Court, AND Ming's navy.
At this time Admiral Yi's headquarter was cut off from the Royal Court's help, but apparently not from its hand asking for aid. A Joseon commander usually is given a right to collect tax or resources from surrounding villages. Admiral Yi, who never really had any access other than his own Cholla province, usually had to divide the limited provision between his navy and the King's court. How he saved up enough to build his navy's strength from 50 something to over 200 despite all this, I'll never know.
When Chen Lin joined him, he was also ordered to feed Ming's navy too, although Ming's soldiers never really found it too much trouble to just take it from Korean citizens by force. The biggest enemy of Joseon navy was not Japanese, but the hunger resulted from the King's court and Ming's navy sucking on their already limited supply. Yet the Admiral Yi never lost his control over his soldiers, nor their respect for him.
So forgive me if I think the Admiral Yi is the greatest naval commander in the history of mankind over Nelson, Drake, and whomever you can think of.
Edited by kevpkevp - 09-Mar-2007 at 00:21