After WWII, many territories of Japan were liberated by the allies. Korea was one such territory whose possession could not be agreed upon. The US and the Soviet Union agreed to split the territory in half with the US on the south side and the Soviet Union on the North. The border was drawn on the 38th parallel. After the two countries' withdraw, the two territories became separate countries. North Korea and South Korea. There were many skirmishes on across the 38th parallel.
The invasion began on June 25, 1950, when 75,000 North Korean troops crossed the 38th parallel after an artillery barrage on the south. The North Korean invasion almost took over the entirety of South Korea. they hoped for a quick surrender by the south. Most US officials did not consider intervening in the war. The war was going badly for the allies. North Korea had a well-trained, well-equipped army. South Korea had an ill-equiped, confused army that wanted to flee.
The US Joins
Our first response was to evacuate any US citizens that might be in South Korea. Once the US joined the war on South Korea's behalf the war was solely a defensive one where the goal was to keep communists out of South Korea. By the end of the summer the president decided that the war's new goal was to liberate North Korea from the communists. The strategy was successful at first. An amphibious assault on Inchon pushed North Korea out of Seoul and into their own territory. China helped North Korea with the support of Soviet AA (anti-aircraft) guns
Liberating North Korea
As the Us Pushed all the way to the Yalu river China prepared for a full scale war against the US. The allies backed off as the Soviets would have been involved in such a war which would have probably started nuclear war.
It took 2 years of negotiations to come to an agreement about a cease fire. The main problem was what both sides should do with their POWs (Prisoners of war). Only after President Eisenhower was elected could a cease fire be agreed on. The armistice allowed POWs to go where they like after the war and drew a new border which gave South Korea and extra 1,500 square miles of territory. A 2 miles wide demilitarized zone was also created. This is a no man's land between north and south Korea.
General Douglas MacArthur was the main commander for the Korean war. After the appointment of Matthew Ridgeway as the new commander, the morale of the US troops improved. Ridgeway took a different strategy, which was to heavily fortify a line just above the 8th parallel and send occasional offenses across the line. About 3 million out of 5 million deaths were civilians.