This is my very first post on this forum, and I'm looking forward to hear your opinion on this.
First of all, sorry for my bad English.
Among professional historians, there are several rival opinions about what prompted Toyotomi Hideyoshi to invade Korea. In accordance with one of them, Toyotomi and thus tried to strengthen his domestic political position (a third-party version is prominent historian Arano Yasunori). In accordance with another, he will remove the possible opposition situation: if in the European countries the number of the nobility fluctuated in the region of 1.5-3% (in Zhechi Pospolita, glorious for its nobleman's freedom and permanently on the verge of anarchy, the number of the nobility was ca. 8% of the total population), in Japan the size of the caste was equal to about 10% of the total population - after that, thousands of younger sons who did not receive soyen (the same as the major) and the ronin who lost their suzeraines, zanim were robbery and robbery, walked into criminal gangs and pirates borokudan Waco, became mercenaries in China and Korea.
Be that as it may, a well-armed Japanese expeditionary force, which, among other things, possesses firearms, defeated the incompetent Joseon's army within four months. Only the successful actions of the brilliant naval commander Yi Sun-sin made it possible to cut supply through the Tensen Kaikyo: in July 1592, the Joseon's fleet near Khansan Island not losing even a single ship, using smaller forces (56 ships from Li Sun-sin against 133 ships from Kiki Yoshitaki) defeated (the Japanese lost 66 ships) the Japanese fleet. The Chinese Emperor Wanli sent a 30-thousand-strong army to Korea in January 1593, which defeated the excess supply and inferior to the Chinese army, Konishi Yukinaga (about 18 thousand people) in the second battle of Pyongyang. The Japanese began to withdraw troops to the southeastern parts of the peninsula, defeating the Chinese troops, entrenched in the province of Gyeongsang and in the summer of 1593 entered into negotiations with the Chinese. The war was replaced by a two-year truce, and Korea was de facto divided between Japan and China.
And now comes the alternative: suppose Yi Sun-sin dies six years earlier - for example because of tuberculosis on May 21, 1592, just two days prior to the war. The new commander-in-chief of the fleet is Von Gyun, who did not manage to slip any serious obstacle to supplying the Japanese expeditionary army in Korea. The Japanese are drawing additional forces into Korea, the number of Japanese troops is over 200 thousand. The Konishi's army fights off the Chinese January attack of 1593 at Pyongyang with the same ease as the summer of 1592. The Japanese go to the border of the Ming Empire in the lower reaches of the Yalu River. The war is moving into a protracted phase, by the beginning of 1594 the Sino-Japanese negotiations are under way. In the 1590s, the Japanese invaders fought with the Liibong partisans, and on the northern borders - with the Jurchen nomads. In 1598 Toyotomi dies, Tokugawa Ieyasu - one of the members of the regency council under the young Toyotomi Hideyori - usurps power and becomes first the "Great Minister" of Daidzyo-daijin, and five years later - the shogun.
This is how Korea has become part of the Japanese empire.
Any ideas what will happen next?