Five Things to Know About the Korean War
1950-1953

1. An Ideological Civil War between Communism and Democracy: Japan occupied Korea as a colonial power from 1910 until 1945. After Japan was defeated in World War II, Korea was liberated and placed under an international trusteeship led by the US and the communist Soviet Union. These two global superpowers had very different views of what a future independent Korea should look like. Unable to resolve the ideological battle between communism and Democratic capitalism, the Korean peninsula was split horizontally at the 38th Parallel, with the Soviet Union controlling the north and the United States controlling the south. This was to be temporary, until a framework for an independent, unified Korea could be produced by the newly-chartered United Nations. The United Nations failed to produce a plan acceptable to the Soviet Union, and so elections were held in the U.S.-occupied South only, leading to the formation of the Republic of Korea (“South Korea”) in 1950. Shortly after, the Democratic People’s Republic of Korea, a socialist state, was founded in North Korea, led by Kim Il Sung.
2. North Korea Invades Across the 38th Parallel: In June of 1950, North Korean forces crossed the border at the 38th parallel and captured South Korea’s capital city, Seoul, 30 miles to the south. The US and then-President Truman were deeply concerned about the spread of communism and wanted to stop the Soviet Union from gaining additional territory. The United Nations Security Council quickly authorized the dispatch of military forces to Korea. The Soviet Union, which had been boycotting the Security Council for not including the communist People’s Republic of China (China), but rather the Republic of China (Taiwan), did not vote. In June 1950, President Truman ordered US troops to Korea. Ultimately, 21 countries participated in the action, with the U.S. providing over 90% of the UN military personnel.
3. China Enters to Support the Communists: In the first two months of the war, the North Korean forces pushed South Korean and American forces almost the southern tip of Korea. But in September, UN forces counterattacked by sea, capturing the city of Incheon, which cut off North Korean forces and supply lines in the south. The UN and American forces moved north, invading North Korea and, in an effort to eliminate the Communist threat, pushed almost to the northern border with China. But in October 1950, China invaded, secretly crossing the Yalu River to join the North Korea. In November, 120,000 Chinese forces surprised 30,000 US Marines, surrounding them at the Chosin Reservoir. A 17-day battle in extreme freezing weather, as low as -25F degrees, ensued. UN forces, supported by the US Army’s Task Force Faith, were able to break out and withdraw back across the 38th parallel.
4. Ground and Arial Battles: Seoul was recaptured by UN forces in March 1951, and was defended successfully in April 1951. The last two years of the ground battle were spent mostly around Seoul and the 38th Parallel with fierce fighting in Korea’s rugged hills and ridges. The Air Force became a separate branch of the US military in 1947, and US and UN pilots took the battle to the air. A massive UN bombing campaign assaulted North Korea, targeting power plants and, ultimately, every major city. Jet fighters also faced each other in air-to-air combat for the first time in history, with US pilots flying F-86 aircraft facing off against Chinese and (covertly) Soviet pilots flying MiGs.
5. An Uneasy Peace Leading to the “Cold War:” In July 1953, the countries involved in the conflict signed an armistice ending the war and agreed to an ongoing division between North and South Korea. No peace treaty was ever signed, so technically, the two nations are still at war. The war was short but costly. 0.65-1.5 million soldiers and 2-3 million civilians from North and South Korea were killed. Over 36,000 US troops were also killed, including 436 from Utah, and 100,000 were wounded. 7,500 Americans remain unaccounted for. Today, South Korea is a democratic republic with a presidential system of power. North Korea is a communist monarchy, ruled by Kim Jong-Un, the grandson of its founder. The nations remain divided at the 38th Parallel. The desire to “contain” the spread of Communism, especially by neutralizing the Soviet Union, became the guiding principal of US foreign relations. The tense period from 1947 to 1991 is known as the Cold War because there was no direct fighting between the two superpowers. It was characterized by espionage, the second Red Scare (McCarthyism) from 1947-1957, the Cuban Missile Crisis in 1962, the Space race and moon landing (1955-1969), the Soviet war in Afghanistan (1979-1989), advances in military technology and capacity, and the buildup of nuclear weapon arsenals. The Cold War ended with the fall of the Berlin Wall and dissolution of the Soviet Union in 1991.

https://en.wikipedia.org/wiki/Korean_War
https://www.history.com/topics/korea/korean-war 
https://www.history.com/this-day-in-history/armistice-ends-the-korean-war 
https://en.wikipedia.org/wiki/United_States_military_casualties_of_war 
https://en.wikipedia.org/wiki/List_of_battles_with_most_United_States_military_fatalities 
https://www.dpaa.mil/Our-Missing/Korean-War/ 
https://www.uen.org/utah_history_encyclopedia/k/KOREAN_WAR.shtml