Ever since Sept 1948, when the Democratic People's Republic of Korea (N Korea) was founded, Kim Il Sung had been actively seeking permission from Josef Stalin to invade the South and reunify the penisular by force. Stalin was not particularly enthusiastic; fearful of provoking the Americans into an escalated war. However by the spring of 1950, after visits to Moscow, Kim finally managed to persuade Stalin to come round; promising that a large S Korean block of sympathizers would quickly help to finish off the South as the N Korean forces attacked, long before the Americans could intervene decisively. Stalin gave his nominal approval, contingent upon approval from Mao Zedong as well.
So in May 1950, Kim visited Beijing and obtained Mao's reluctant consent. Although the Chinese were not enthusiastic either, they felt that they owed the N Koreans a favour. N Korea had provided much help to the People's Liberation Army (PLA), during its takeover of Manchuria a few years earlier and large numbers of N Koreans served with the PLA; during the just-concluded Chinese civil war. Then there was also the matter of supporting a fellow revolutionary in this (probably) first foreign policy act of the (less than one year old) People's Republic of China. Of note, Kim told Mao, when asked, that Chinese troops were not needed, even if the Americans got involved.
In the run-up to the invasion though, the N Koreans and Soviets seriously irritated the Chinese, as N Korea seeked to conceal the full extent of their preparations fr the Chinese. Returned N Korean personnel fr the PLA were 'isolated' from the preparations. The N Koreans even resorted to shipping in Soviet war material via the sea, to avoid transporting them through Chinese territory.
Although there were indications on the ground that the N Koreans were preparing for a major operation, the Americans (or anyone else) did not really take notice. So on Sunday, 25 June 1950, at 3.30 .a.m., seven N Korean divisions, supported by 150 tanks (including 125 T-34s), rolled across the border. The lightly-armed S Korean forces were immediately thrown into chaos and pushed back.
The Americans hesitated for 2 days until 27 June, before President Harry Truman ordered all US naval and air units in the region to support the S Korean forces. On the same day, the United Nations passed a resolution (the Soviets were absent, protesting the exclusion of the PRC from the UN) to furnish forces to support S Korea. And in a concurrent move, which the Chinese deemed provocative, the US 7th Fleet was ordered to patrol the Taiwan Straits and stopped all military activity in the area.
Then on 30 June, as the S Korean forces continued to collapse, President Truman ordered US ground forces to be committed to Korea as well. On 7 July, the UN requested for the US to direct operations in Korea, with the aim of assisting the Republic of Korea (RoK) 'in self-defense and restoring international peace and security to the area'. General Douglas MacArthur was appointed as the commander-in-chief of the newly-formed UN Command.
American ground divisions were thrown into the conflict. These included the half-trained and understrength 24th and 25th Infantry Divisions and the 1st Cavalry Division from Japan, as well as the stronger 2nd Infantry Division from Fort Lewis and the 1st Provisional Marine Brigade (organized around the 5th Marines) from Camp Pendleton. Though initially the US forces were driven back, by September, a shaky defensive line was held along the Naktong river, forming the Pusan Perimeter. The initial lowly estimates of the N Korean fighting abilities were very quickly revised upwards.
On 13 Sept, the counterattack began, at Inchon. The US X Corps, led by the 1st Marine Division, landed successfully, drove inland, and cut off the N Koreans. The US Eight Army also broke out of the Pusan perimeter within days and linked up with the landing force. The N Korean offensive was broken.
On 27 Sept, even as fighting still raged around Seoul, the Joint Chiefs issued their instructions to General MacArthur. There were some changes before a final version was issued. One change was from 'UN forces should not be permitted to operate into areas close to the Manchurian and Soviet borders' to 'UN forces should not cross those borders'. Another change was from 'non-RoK forces shld in no circumstances be used in those border regions' to merely just 'it should be the policy not to employ non-RoK forces in those regions'. Two very glaring changes, in hindsight. The instructions were also ambigious in certain aspects, like in the definition of what constituted an area 'close' to the border e.g. The contingency of Chinese intervention north of the 38th parallel was also not covered. An item of particular interest was that though the instructions authorized MacArthur to operate in N Korea, nothing in them required him to occupy the whole country.
MacArthur planned for a second amphibious landing; this time at Wonsan (on the east coast) by the X Corps, which would then strike westwards (towards Pyongyang) and joined up with the Eight Army advancing northwards to trap and destroy the N Korean forces south of the Pyongyang-Wonsan line. All UN forces would then stop at the Chongju-Yongwon-Hamhung line. Only RoK forces would operate north of that. The plan was criticized but MacArthur was adamant. Finally due to an aura of infallibility from his earlier Inchon landing strategy (which was also hotly debated but turned out to be a huge success), he managed to push through the plan.
(In any event, delays in loading up the 1st Marine Division at Inchon as well as the huge minefield at Wonsan meant that the X Corps did not land and partake in action again until 25 October, after the fall of Pyongyang. S Korean forces by then had took Wonsan and even reached Hamhung and Hungnam, further north along the east coast.)
The Eight Army commenced its attack across the 38th on 8 October, 1950. On the east coast, S Korean troops had crossed the border on the 1st. By the 10th, the S Korean forces had secured Wonsan. By the 18th, they had also reached and secured Hamhung and Hungnam. On the west coast, the I Corps occupied Pyongyang on the 20th, after breaking through N Korean lines at Kumchon. On the same day, the 187th Airborne RCT (regimental combat team) was air-dropped onto Sukchon and Sunchon, in a (failed) attempt to intercept the fleeing N Koreans.
On 15 October, MacArthur flew (irritably) to Wake Island to meet with President Truman, as well as other generals. From his comments at the meeting, it would seem that he held very very low opinions on the Chinese forces, which was certainly widespread amongst Westerners in that time-period. Nobody contradicted him certainly. MacArthur made the grand announcement that organized resistance would end by Thanksgiving and the Eight Army would be 'home by Christmas'.
Since the X Corps was to land too late to do any good as in the original plan, MacArthur decided to go for a new stop line, one that was even closer to the Manchurian border. In the west, the Eight Army would advance to the Songchon-Koin-dong-Pyongwon line. In the east, the X Corps, as well as the I RoK Corps, would advance on its own onto the Toksil-li-Pungsan-Songjin line. The two forces would be divided by a (supposedly) uncrossable mountainous range.
The stage was set, for China's grand (re)entry onto the world stage.
Reference:-
The Dragon Strikes-China and the Korean War: June-Dec 1950 by Patrick C. Roe
So in May 1950, Kim visited Beijing and obtained Mao's reluctant consent. Although the Chinese were not enthusiastic either, they felt that they owed the N Koreans a favour. N Korea had provided much help to the People's Liberation Army (PLA), during its takeover of Manchuria a few years earlier and large numbers of N Koreans served with the PLA; during the just-concluded Chinese civil war. Then there was also the matter of supporting a fellow revolutionary in this (probably) first foreign policy act of the (less than one year old) People's Republic of China. Of note, Kim told Mao, when asked, that Chinese troops were not needed, even if the Americans got involved.
In the run-up to the invasion though, the N Koreans and Soviets seriously irritated the Chinese, as N Korea seeked to conceal the full extent of their preparations fr the Chinese. Returned N Korean personnel fr the PLA were 'isolated' from the preparations. The N Koreans even resorted to shipping in Soviet war material via the sea, to avoid transporting them through Chinese territory.
Although there were indications on the ground that the N Koreans were preparing for a major operation, the Americans (or anyone else) did not really take notice. So on Sunday, 25 June 1950, at 3.30 .a.m., seven N Korean divisions, supported by 150 tanks (including 125 T-34s), rolled across the border. The lightly-armed S Korean forces were immediately thrown into chaos and pushed back.
The Americans hesitated for 2 days until 27 June, before President Harry Truman ordered all US naval and air units in the region to support the S Korean forces. On the same day, the United Nations passed a resolution (the Soviets were absent, protesting the exclusion of the PRC from the UN) to furnish forces to support S Korea. And in a concurrent move, which the Chinese deemed provocative, the US 7th Fleet was ordered to patrol the Taiwan Straits and stopped all military activity in the area.
Then on 30 June, as the S Korean forces continued to collapse, President Truman ordered US ground forces to be committed to Korea as well. On 7 July, the UN requested for the US to direct operations in Korea, with the aim of assisting the Republic of Korea (RoK) 'in self-defense and restoring international peace and security to the area'. General Douglas MacArthur was appointed as the commander-in-chief of the newly-formed UN Command.
American ground divisions were thrown into the conflict. These included the half-trained and understrength 24th and 25th Infantry Divisions and the 1st Cavalry Division from Japan, as well as the stronger 2nd Infantry Division from Fort Lewis and the 1st Provisional Marine Brigade (organized around the 5th Marines) from Camp Pendleton. Though initially the US forces were driven back, by September, a shaky defensive line was held along the Naktong river, forming the Pusan Perimeter. The initial lowly estimates of the N Korean fighting abilities were very quickly revised upwards.
On 13 Sept, the counterattack began, at Inchon. The US X Corps, led by the 1st Marine Division, landed successfully, drove inland, and cut off the N Koreans. The US Eight Army also broke out of the Pusan perimeter within days and linked up with the landing force. The N Korean offensive was broken.
On 27 Sept, even as fighting still raged around Seoul, the Joint Chiefs issued their instructions to General MacArthur. There were some changes before a final version was issued. One change was from 'UN forces should not be permitted to operate into areas close to the Manchurian and Soviet borders' to 'UN forces should not cross those borders'. Another change was from 'non-RoK forces shld in no circumstances be used in those border regions' to merely just 'it should be the policy not to employ non-RoK forces in those regions'. Two very glaring changes, in hindsight. The instructions were also ambigious in certain aspects, like in the definition of what constituted an area 'close' to the border e.g. The contingency of Chinese intervention north of the 38th parallel was also not covered. An item of particular interest was that though the instructions authorized MacArthur to operate in N Korea, nothing in them required him to occupy the whole country.
MacArthur planned for a second amphibious landing; this time at Wonsan (on the east coast) by the X Corps, which would then strike westwards (towards Pyongyang) and joined up with the Eight Army advancing northwards to trap and destroy the N Korean forces south of the Pyongyang-Wonsan line. All UN forces would then stop at the Chongju-Yongwon-Hamhung line. Only RoK forces would operate north of that. The plan was criticized but MacArthur was adamant. Finally due to an aura of infallibility from his earlier Inchon landing strategy (which was also hotly debated but turned out to be a huge success), he managed to push through the plan.
(In any event, delays in loading up the 1st Marine Division at Inchon as well as the huge minefield at Wonsan meant that the X Corps did not land and partake in action again until 25 October, after the fall of Pyongyang. S Korean forces by then had took Wonsan and even reached Hamhung and Hungnam, further north along the east coast.)
The Eight Army commenced its attack across the 38th on 8 October, 1950. On the east coast, S Korean troops had crossed the border on the 1st. By the 10th, the S Korean forces had secured Wonsan. By the 18th, they had also reached and secured Hamhung and Hungnam. On the west coast, the I Corps occupied Pyongyang on the 20th, after breaking through N Korean lines at Kumchon. On the same day, the 187th Airborne RCT (regimental combat team) was air-dropped onto Sukchon and Sunchon, in a (failed) attempt to intercept the fleeing N Koreans.
On 15 October, MacArthur flew (irritably) to Wake Island to meet with President Truman, as well as other generals. From his comments at the meeting, it would seem that he held very very low opinions on the Chinese forces, which was certainly widespread amongst Westerners in that time-period. Nobody contradicted him certainly. MacArthur made the grand announcement that organized resistance would end by Thanksgiving and the Eight Army would be 'home by Christmas'.
Since the X Corps was to land too late to do any good as in the original plan, MacArthur decided to go for a new stop line, one that was even closer to the Manchurian border. In the west, the Eight Army would advance to the Songchon-Koin-dong-Pyongwon line. In the east, the X Corps, as well as the I RoK Corps, would advance on its own onto the Toksil-li-Pungsan-Songjin line. The two forces would be divided by a (supposedly) uncrossable mountainous range.
The stage was set, for China's grand (re)entry onto the world stage.
Reference:-
The Dragon Strikes-China and the Korean War: June-Dec 1950 by Patrick C. Roe
