Consider the weakness of the Chinese military. Firstly, the army had sustained a high number of casualties and had experienced a decline in troop morale. Although the Chinese had scored a major victory in its December 1950 offensive, it had lost the “backbone of [its] troops”. The failures of the 4th and 5th Phase Offensives in early 1951 added to this high death rate, with some 85,000 troops lost in the 5th Phase Offensive alone. As for troop morale, it had fallen due to fatigue and insufficient food; in addition to the harshness of the terrain and the cold Korean winter. Consequently, the Communist forces could not sustain their military advances and were unable to win a quick and decisive victory over the UN forces.
Secondly, the army had been overstretched. This was especially due to the long supply lines and a lack of logistic support. As argued by Zhang Shu Guang, China did not have a standard logistical system before the Korean War, and had merely relied on capturing enemy materials and acquiring food from the local people. Although the Chinese had set up a logistical department to handle the Korean War, it was small and poorly-staffed, highly inadequate for managing and transporting supplies. In addition, the department, or Dong Hou as it was known, failed to meet the needs of the combat troops. This was because the materials shipped to North Korea were not quickly dispersed, with large amounts being destroyed by the UN air raids. The supplies were also transported too slowly, due to the slow movement of trucks and the long distances between depots and troops. It was only by the middle of 1951 that a coherent logistical system was in place. Consequently, the Communist forces were not able to fully utilise this system to supply their troops, resulting in their failure to defeat the US-led forces.
Poor air support also resulted in Chinese weakness against the Americans. This was crucial not only in supporting the transport of logistic supplies, but also in the support of ground troops in battle. As the Chinese air force was newly established and lacked combat experience, it was inadequate in providing such support. The Soviets therefore provided protection along some of the transportation lines. This assistance was however limited to the North Korean interior due to the USSR’s fear that the move would have an adverse effect on world opinion. As a result, many of the Chinese supply lines remained open to American interdiction and many supplies were lost. With regards to ground support, this was also denied as the American air force had destroyed most of the airfields which China had constructed in North Korea in order to support its 1951 offensives. Consequently, Communist forces had to embark on their 5th Phase Offensive in April 1951 without the planned air support.
A fourth reason why China had failed to defeat the US-led forces was attributed to strategic miscalculations during its 1951 offensives. For instance, in the key February offensive of Chipyong-ni, Chinese leaders were of the mistaken perception that the UN forces would retreat from battle. They therefore did not consider that the US would reinforce Chipyong-ni, resulting in a Communist retreat. The Chinese forces also lost the April offensive partly due to ineffective coordination between the artillery and infantry units, as well as employing troops with little combat experience. Such military defeats cost the Chinese-led forces dearly, and resulted in their retreat back to the 39th Parallel.
Consider now the effectiveness of the US-led forces. Firstly, they were led by a capable leader in the person of UN Supreme Commander General Matthew B. Ridgway. According to Roy Appleman, Ridgway was both an “inspiring leader of men” and a “pragmatic commander”, knowing how to balance between military strategy and winning the hearts of his men. Indeed Ridgway had taken command of a defeated and demoralised army in December 1950, fighting on despite the loss of Seoul, before re-organising the army and pursuing the Chinese back to the 38th Parallel. He was also responsible for the establishment of a strong defence line across the breadth of Korea, which held the Chinese to a stalemate for more than two years.
Secondly, the US-led forces were effective because they presented a coherent military strategy to combat the Chinese. One such method was the use of closely-supported defence lines to hold out against the enemy. Take for instance control of the critical Kansas-Wyoming defence line as ground “suitable for a strong defence”. There was also the Ridgway plan of successive defence lines, allowing UN withdrawals from the front line, and at the same time forcing the Chinese to re-deploy, keeping them off-balance and susceptible to artillery fire and air strikes. Indeed a key application of this strategy was the successful defence of Chipyong-ni and Wonju through the close-knit system of contact between ground units. This allowed the US to reinforce Chipyong-ni, a key location in the defence of Wonju. Consequently, in preserving Wonju, the UN forces had prevented a breach in their defence line and struck a significant blow against the Chinese 4th Phase Offensive, giving them an opportunity to advance into Seoul.
Another factor contributing to the US army’s effectiveness was its vast superiority in technology, air support and transportation speed. As Robert Leckie noted, the superior and modern firepower of the US-led forces had been a determining factor in the vast number of Communist casualties. In addition, massive air strikes had resulted in the devastation of North Korean transportation lines, denying the Chinese-led forces their much-needed supplies. This was in stark contrast to the speedy resupplying of the UN forces, due to the vast availability of its transport equipment and its uninterrupted supply lines.
Political influence was a key factor that explained why the Chinese were unable to defeat the American-led forces. Firstly, it has been argued that the Chinese setbacks in 1951 were directly caused by erroneous decisions made by the top leadership. According to Zhang Shu Guang, Chinese leader Mao Zedong had overestimated the extent of damage that the army could cause. Zhang felt that Mao’s overrating of the early Chinese successes resulted in an overstretching of the army.  The Chinese leader had therefore set an unrealistic and ambitious goal of driving the UN forces to the 36th Parallel. This was against the better judgement of field commander Peng Dehuai, who had warned Mao that the troops needed rest, resupplying and reorganisation.
Secondly, the Chinese military had been affected by internal and external political pressure in its strategic manoeuvres. Internally, it had overvalued the importance of political prestige and the crossing of the 38th Parallel. According to Zhang, this resulted in political considerations “overwhelming” any realistic military calculation. Consequently, it was more difficult for Chinese commanders to be flexible in their military strategy, as they had to cater more to public opinion than to the actual viability of the military position. Externally, Chinese leaders were under constant pressure from the North Korean leaders, who had pushed the Communist forces towards riskier actions than could be afforded. Consequently, this clouded China’s assessments of what was in its best interests.
A key political influence on the war was the firing of General Douglas MacArthur as UN Supreme Commander. MacArthur’s replacement by Ridgway resulted in a more moderate approach to the war. It allowed for Ridgway’s containment strategy to be adopted, a strategy based on defence lines and resulting in the 1951-53 stalemate. This was in stark contrast to MacArthur’s “all or nothing” recommendations, that the US either fight an expansionary war to defeat China completely, or else announce a total withdrawal from Korea. Consequently, the change in commanders directly affected the execution of American plans. Indeed Ridgway’s containment strategy formed the basis by which the Chinese were stopped from defeating the UN forces, instead reaching the 1951 stalemate situation near the 38th Parallel.
In conclusion, the Chinese army in 1951 had failed in its attempt to defeat the US-led forces in Korea despite an earlier string of successes. This failure was due to an interplay of various different reasons, each factor being linked to another in a different way. Of particular importance were the military effectiveness of the opposing armies and the political climate which determined how these armies operated. Consequently, there was no single reason that led to the stalemate situation along the 38th Parallel and the Chinese failure to overcome the American-led forces in a quick and decisive battle.
The above essay was written by Mark Lim Shan-Loong on 13th September 1999.
Appleman, Roy E. Ridgway Duels for Korea. USA: Texas A&M University Press: 1990.
Blair, Clay. “The Korean War: Background and Overview.” Security in Korea: War, Stalemate, and Negotiation. Eds. Phil Williams et al. USA and UK: Westview Press, 1994. 39-52.
Edwards, Paul M. The Korean War. Florida: Krieger Publishing Company, 1999.
Leckie, Robert. Conflict: The History of the Korean War. New York: Da Capo Press, 1996.
Schnabel, James F. United States Army in the Korean War - Policy and Direction: The First Year. Washington: US Army Office of the Chief of Military History, 1972.
Spanier, John S. “The Politics of the Korean War.” Security in Korea: War, Stalemate, and Negotiation. Eds. Phil Williams et al. USA and UK: Westview Press, 1994. 69-100.
United States Army. Overview of the Korean War. 1989. Online. Center of Military History. Available. http://www.koreanwar.org/html/overview_of_the_war.html. 9 Sep 1999.
Zhang, Shu Guang. Mao’s Military Romanticism: China and the Korean War, 1950-1953. USA: University Press of Kansas, 1995.
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 Zhang, Shu Guang. Mao’s Military Romanticism: China and the Korean War, 1950-1953. USA: University Press of Kansas, 1995. pp. 130-2.
 ibid. p.131.
 ibid. p152.
 ibid. p.165.
 ibid. pp. 165-7.
 ibid. p.177.
 Leckie, Robert. Conflict: The History of the Korean War. New York: Da Capo Press, 1996. p. 286.
 Zhang, Shu Guang. Mao’s Military Romanticism. p.142.
 ibid. p.149.
 Appleman, Roy E. Ridgway Duels for Korea. USA: Texas A&M University Press: 1990. p.580.
 ibid. pp. 579-80
 United States Army. Overview of the Korean War. 1989. Online. Center of Military History. Available. http://www.koreanwar.org/html/overview_of_the_war.html. 9 Sep 1999.
 Appleman, Roy E. Ridgway Duels for Korea. p. 449.
 Zhang, Shu Guang. Mao’s Military Romanticism. p.142.
 Leckie, Robert. Conflict. pp.291-2.
 Zhang, Shu Guang. Mao’s Military Romanticism. p.153.
 ibid. p.137.
 ibid. p. 153.
 Spanier, John S. “The Politics of the Korean War.” Security in Korea: War, Stalemate, and Negotiation. Eds. Phil Williams et al. USA and UK: Westview Press, 1994. 69-100. pp.87-8.