The Korean Demilitarized Zone is a strip of land running across the Korean Peninsula that serves as a buffer zone between North and South Korea which runs along the 38th parallel north. The DMZ cuts the Korean Peninsula roughly in half, crossing the 38th parallel on an angle.
...[T]he border between North and South Korea in the DMZ, or Demilitarized Zone -- ironically named as it is considered one of the most heavily-fortified borders in the world.
Mustering three field armies of some 700,000 men, the Chinese conducted spring offensives in April 1951 but
met determined resistance on the ground, from the air and from the sea. By the summer of 1951, the battle lines
were drawn and a stalemate ensued.
The Republic of Korea Army's II Corps and U.S. 2nd Infantry Division were overrun and decimated and the U.S. Eighth Army began the longest retreat in U.S. Army history— one made possible through the heroic actions of Turkish forces to stall the Chinese onslaught for two days at the end of November.
The U.S. Air Force secured the command of the air from an early stage of the [Korean] war, after which it launched bombing campaigns to prevent the North Korean Army from marching southward. As the war dragged on, the U.S. military employed massive air bombings in close air support of its troops on the ground.
At the end of World War II, Korea was divided at the 38th parallel into Soviet (North Korean) and U.S. (South Korean) zones of occupation. In 1948 rival governments were established: The Republic of Korea was proclaimed in the South and the People's Democratic Republic of Korea in the North.
The North transitioned quickly with help from the USSR but still had some ideological differences. The South transition was a bit more chaotic, even with the extra guidance from the USA. Neither the USA nor the USSR understood what Korea wanted; and all three nations had different definitions of what independence meant.
Mass killings of civilians began before the outbreak of the Korean War in June 1950. These killings reflected the heightened tensions that peaked after the Korean peninsula was divided and two separate Korean governments were established north and south of the 38th parallel.
Following World War II, the Korean peninsula was divided along the 38th parallel, with the creation of communist-backed North Korea and the anti-communist Republic of South Korea. On June 25, 1950, North invaded South, leading to the outbreak of the Korean War.
The 38th parallel was the dividing line between North Korea and South Korea and the focal point of fighting during the Korean War.
Japan's 1945 surrender to the Allied Powers at the end of World War II marked the end of its imperial rule over Korea, and the start of poor relations between the two Koreas that would lead them to war in 1950.