Sadae' means literally, to 'serve the great.' It was the political and philosophical system in which Korea paid tribute to China during the Chosôn dynasty, and it had far reaching consequences in both Chosôn culture and politics.link
We have an excellent article on this matter by a (infamous?) site called kimsoft.
the Korean nations – Silla, Koryo, Chosun, and the Republic of Korea practiced Uncle Tomism with China, Japan, Russia, and the United States.
In 1231 the Mongols invaded Korea and after 25 years of struggle the royal family surrendered by signing a treaty with the Mongols. For the following 100 years the Goryeo ruled, but under the interference of the Mongols.
Korea had to pay tribute to Monglue. For instance, she had to send virginal women.
When the Manchus rose up against Ming China, who asked Joseon for assistance, King Gwanghaegun, mindful of the assistance rendered by the Chinese in Joseon's struggle against the Japanese, promptly sent an army of 10,000. However, when it became obvious the Manchus would be victorious, Joseon quickly surrendered to avoid retaliation>link
Dorgon occupied Ganghwa Island in a day and captured the second son and concubines of King Injo, which made him offer his submission. King Injo yielded up three pro-war officers to Qing.
The following were the conditions of peace:
Korea becomes a dependency of the Qing Dynasty.
Korea breaks away with the suzerain Ming.
Korea offers the first and second sons of King Injo, and sons or brothers of ministers as hostages.
Korea pays tribute to Qing as she has done to Ming.
Korea will serve in the war against Ming.
Korea offers army and ships to attack an island.
Qing does not allow Korea to build castles without restraint.
Qing allows Korea to trade with Japan.
Hong Taiji set up a platform in Samjeondo--the upper reach of the Han River. At the top of the platform he accepted King Injo's surrender. King Injo kowtowed to him and begged his forgiveness.
Based on this treaty, Korea had to send 3000 beautiful women to Qing until 19 century,
The institution of kisaeng or kinyô was firmly established in Korean society by Koryô dynasty (918-1392) and continued throughout Chosôn dynasty (1392-1910)link
While concluding the treaty, the king of Korea had to kow-tow 9 times in a way that the head touched the ground..[the photo]link
Korea had to pay tribute to China 4 times a year until 1644.
After that she had to do it every year.
Ryukyu paid the tribute every two years,Thailand every 3 years, Vietnam every 3years10 years, Laos every 10 years.
Korea was the most faithful to China and an honor student of China..
Tthe king of Korea had to go and welcome the envoy of Qing , kneeling down at the 迎恩門, which literally means the gate of welcome favour.In front of this gate, the independence gate was built[the photo}:Korea became independent of Qing.
Not long after Koryo reached a peace agreement with the Mongols, King Wonjong, thinking he could strengthen royal authority within Koryo, sought permission for his son to wed a Yuan princess. In the spirit of Kublai Khan's policy of reconciliation with his vassal states, the Mongols granted his request. Koryo's crown prince, later to become King Ch'ungnyol, subsequently married a daughter of Kublai Khan; the first Mongol queen of a Koryo king. During the crown prince's visit to the Yuan capital the Mongol court invested him as the King of Shenyang.
Since no king could rule two territories simultaneously, and since Yuan emperors could enthrone or depose kings at will, frequent and bitter struggles broke out between Koryo kings, their heirs and the King of Shenyang over succession to the Koryo throne. This divisive Mongol policy produced a politically turbulent and unstable environment in Koryo. The degradation of the Koryo royal house virtually erased any enhancement of royal authority. The Koryo king no longer ruled as an independent monarch over his own kingdom, but occupied a fixed position within the Yuan empire. The royal houses of the two nations became as a single family.
During this period, Koryo kings took Mongol names, wore their hair in Mongol style, wore Mongol dress, and used the Mongol language. Once the Mongols established their domination, Koryo's crown princes regularly traveled to the Yuan court at Khanbalik where they were obliged to marry a Mongol princess and live until the death of the reigning king in Koryo. Through this system, the Koryo royal family became so thoroughly Mongolized that Yuan emperors had little to fear from the Korean kingdomproject
By the way, the name of Korea as Eastern Land of Courtesty was gifted by China, according to this
Kim soft continues.
the Papal Museum of Nationalities in Rome (Curia Romana) exhibits the Hwang White Paper, a petition by a Korean Catholic, Hwang Sa Young (황사영) written in 1801:
Chosun is economically bankrupt and powerless, and we wish to accept the Gospel with the help of the Western nations and obtain funds to rescue our people.Chosun is a client-state of China and the Emperor of China is the effective ruler of Chosun. Therefore, Rome should ask the Emperor's permission to send priests to Korea.
The Chosun royal court is weak and about to fall, and so, Chosun should become part of China, and a member of China's royal family should be appointed to rule over Korea.
The Korean people have enjoyed peace for over 500 years and so know nothing about waging war. A crusader army of several hundred warships and 50 to 60 thousands troops should occupy Korea and make evangelical missions safe and easy in Korea.
In short, Hwang and his Christian followers wanted a foreign power to rule Korea because Koreans were too weak to govern themselves. Korean Christians wanted Korea ruled by a foreign power so that they could spread of Word of God in Korea, and openly worked for foreigners bent on plundering Korea even to the point of robbing royal graves.
Korean Uncle Tomism extended to the ruling class. For example, King Kojong donned Russian, German, Japanese, and American military uniforms seeking protection from Russian Tzars, German Keisers, Japanese Emperors, and American Presidents, he went from one protector to another like a chameleon changing its color with the prevailing wind.
(the photo In 1883 a Korean ambassador plenipotentiary has an official audience with U.S. President Arthurこん )
Korea's first pro-American official was Kim Hong Jip (1842-1896), who had served as the Korean minister in Japan and witnessed the rapid Americanization of Japan. Kim drew up a grand scheme to use America as springboard to recover the vast Koguryo territory lost to China and to establish a powerful Korean empire. Kim returned to Korea in 1880 and presented his "Korea Plan" to King Kojong, who warmly accepted the plan.
On March 24, 1882, King Kojong appointed Shin Hun to negotiate a treaty with the United States. The US side was represented by Commodore Robert W. Shufeldt. The negotiation began on April 4 at Chemulpo, and on May 22, the delegates signed a 14-article treaty on the deck of the USS Ticonderoga. This treaty is known as the Chemulpo Treaty, the first article of which proclaims:“There shall be perpetual peace and friendship between the President of the United States and the King of Chosen and the citizens and subjects of their respective Governments. If other Powers deal unjustly or oppressively with either Government, the other will exert their good offices, on being informed of the case, to bring about an amicable arrangement, thus showing their friendly feelings.”
The Chemulpo Treaty guaranteed safety of foreign missionaries and soon the Korean Peninsula was flooded with American Methodist and Presbyterian evangelists eager to spread the Gospel among the Korean populace. King Kojong believed that, of all the foreign powers present in Korea, the United States was the only nation that had no hidden agenda and so, he hired a number of Americans to serve as advisers and officials in his court. The Americans, mostly Christian missionaries, effectively and enthusiastically introduced modern education, medicine, public health, technology, public administration, and democratic ideas. King Kojong truly believed that the United States would abide by the mutual defense clause of the Chemulpo Treaty and welcomed all Americans with an open arm.
the Taft-Katsura Agreement was signed on July 29, 1904. Japan agreed to accept the US presence in Hawaii and the Philippines, and in exchange, the United States agreed to nullify the Chemulpo Treaty and to give Japan a free hand in Korea. When the agreement was signed, Japanese troops were already in Korea in large numbers and the US military had neither the will nor the power to expel the Japanese from Korea, even if it had wanted to.
The Taft-Katsura agreement on Korea is as follows:"Third, in regard to the Korean Question, Count Katsura observed that Korea being the direct cause of our war with Russia, it is a matter of absolute importance to Japan that a complete solution of the peninsula question should be made as a logical consequence of the war. If left to herself after the war, Korea will certainly draw back to her habit of improvidently entering into any agreements or treaties with other powers, thus resuscitating the same international complications as existed before the war.
In view of the foregoing circumstances, Japan feels absolutely constrained to take some definite step with a view to precluding the possibility of Korea falling into her former condition and of placing us again under the necessity of entering upon another foreign war.
Secretary Taft fully admitted the justness of the Count’s observations and remarked to the effect that, in his personal opinion, the establishment by Japanese troops of a suzerainty over Korea to the extent of requiring Korea to enter into no foreign treaties without the consent of Japan was a logical result of the present war and would directly contribute to permanent peace in the East."
After securing the US consent, Japan moved fast and made Korea a Japanese protectorate. Unaware of the secret Taft-Katsura agreement, King Kojong sent Homer Hulbert, an American friend and adviser to the Korean court, to Washington to seek US aid under the Chemulpo Treaty. President Teddy Roosevelt, under whose name the Taft-Katsura agreement was signed, refused to see Hulbert.
President Theodore Roosevelt's official stance was: "The Korean Government was in the position of an incompetent defective not yet committed to guardianship. The United States is her only disinterested friend-but has no intention of becoming her guardian.... We cannot possibly interfere for the Koreans against Japan. . They could not strike one blow in their own defense."
After the Taft-Katsura Agreement, some of the American advisers in King Kojong's court began to work secretly for the Japanese. They believed that Korea would be better off under Japan and worked their best to help Japan annex Korea. Durham White Stevens was one of these American turncoats. Stevens was employed as an adviser to the foreign ministry of King Kojong, while secretly working for Prince Ito Hirobumi, the chief architect of Japan's annexation of Korea. A Korean-American, Chang In-Whan, gunned down Stevens on March 23, 1908, in San Francisco
That's all for today. Remember, I am not a historian, I am just an amateur, so correct me if I am wrong.
The follow up
To reinstate Chinese control in Korea, China advised Korea to conclude a series of commercial treaties with European powers and America. The Korea-U.S. treaty of commerce was concluded on May 22 and signed on June 6, 1882. Korea signed revised treaties with Great Britain and Germany in Seoul on November 26, 1883. The two new treaties, together with the first international treaty concluded with Japan, were most disadvantageous to Korea. In addition, a treaty of commerce was signed with Russia on June 25, 1884, and was followed on August 8, 1888, by the conclusion of another agreement governing Korean-Russian overland commerce. A treaty of commerce with France was signed on June 4, 1886.KSS-USA/hist-map8
Ex-minister Waeber, remaining in Seoul, plotted to persuade King Kojong to take refuge at the Russian legation. Home Minister Yu Kil-jun, meanwhile, conferred with Japanese Minister Komura Jutaro concerning countermeasures that might be taken against Russia. At dawn on February 11, 1896, Kojong and the Crown Prince went to the Russian legation to escape the Japanese menace, and were protected by guards provided by other legations as well. Japanese Minister Komura called on Russian Minister Speyer at the Russian Legation and requested that the emperor return to the royal palace, but Emperor Kojong refused, knowing that he had chosen the lesser of two evils.
At the same time the Korean government, following a proposal made by the Russian minister, appointed Russians as consultants for military training and financial administration. In May, a Korean delegation led by Min Yong-hwan and Yun Ch’i-ho concluded a treaty in Russia with Foreign Minister Lobanoff, agreeing to the following: Russia would protect the Korean monarch and, if necessary, would send additional troops to Korea; the consultants in question would be subject to the guidance of the Russian minister; the two governments would enter into a loan agreement when deemed necessary in view of Korea’s economic conditions; and the Russian government would be authorized to connect its telegraph lines with the Korean telegraph network. With the Korean king in custody, Russia lost no time in implementing the aggressive provisions of the treaty.