North and South Korea had been one nation since the 7th century under the Silla Dynasty. They remained united under the Joseon Dynasty which lasted from 1392 until 1910. The language and culture of the two countries are essentially the same. Korea was one nation until the Korean Peninsula was formally annexed in 1910 by the Empire of Japan. Japan had controlled the Korean Peninsula since it won the first Sino-Japanese War in 1895. Puppet emperors ran Korea on Japan’s behalf until Korea became a Japanese colony from 1910 until after World War II in 1945.
With the Japanese Empire in tatters, Russia took control of North Korea, which it had given up after the Russo-Japanese War in 1904-05. With Japan’s surrender imminent, the United States, already committed to managing the Philippines and other Japanese assets after the war, was charged with delineating an East Asia occupation zone. They decided to cut Korea in half at the 38th parallel latitude and control the Southern half of the country. It included Seoul, Korea’s capital and the Korean Peninsula’s largest city. The decision for administering Post-War Japan was made by two U.S. officials, Charles Bonesteel and Dean Rusk and became part of General Order No. 1.
The Soviets accepted the surrender of the Japanese forces based in northern Korea. Japanese forces in southern Korea gave themselves up to the Americans. Political parties quickly formed in South Korea and created plans for setting up a government in Seoul. However, the U.S. Military Administration saw many of the candidates as having leftist tendencies. They were concerned the entire peninsula would be under communist control after Korean elections in 1948 to reunify the country, which Russia wanted. The U.S. wanted Korea to be democratic and capitalist. The Soviets and the Americans were supposed to arrange and administer the elections, but they didn’t trust each other.
Once World War II was over and the Japanese defeated, the Koreans were looking forward to once again being a free and united nation. But the distrust between the USSR and the U.S. and the dividing line separating Korea into two countries made that impossible. Instead, Syngman Rhee, an American supported, anti-communist leader, declared South Korea an independent nation in May 1948 and he became its first president in August the same year. In North Korea, Kim Il-sung, a former World War II Soviet Red Army major, had been put in charge of what is now North Korea. He officially became the country’s leader in September 1948.
Using the 38th parallel as the line separating North and South Korea was a disastrous choice. Most electrical and heavy industrial resources were located north of the 38th Parallel. The bulk of the agricultural and light industrial resources were concentrated south of the line. This caused both North and South Korea to struggle economically. In an attempt to reunite Korea under communist rule, Kim Il-sung invaded South Korea in 1950. That led to the Korean War which lasted until 1953.
With the help of the United Nation and American troops, South Korea was able to hold off the invading North Korea forces. Over 3 million Korean, Chinese, American and U.N. personnel died in the three-year-long war before the two sides agreed to a truce. Signed in July, 1953 in Panmunjom, the truce called for North and South Korea to accept the 38th parallel as the border between the two countries. The Demilitarized Zone, an electrified area along the 38th parallel monitored by armed guards, prevents people from crossing between the two countries. This arrangement has remained in place for more than 60 years.