page_title: Battle of Chosin Reservoir
section_title: Forces and strategies
hierarchical_section_title: Battle of Chosin Reservoir / Prelude / Forces and strategies
caption_attribution_description: Map of the Battle of the Changjin (Chosin) Reservoir.
context_page_description: The Battle of Chosin Reservoir, also known as the Chosin Reservoir Campaign or the Battle of Jangjin Lake was an important battle in the Korean War. The name "Chosin" is derived from the Japanese pronunciation "Chōshin", instead of the Korean pronunciation.
  Official Chinese sources refer to this battle as the eastern part of the Second Phase Campaign. The western half of the Second Phase Campaign resulted in a Chinese victory in the Battle of the Ch'ongch'on River.
  The battle took place about a month after the People's Republic of China entered the conflict and sent the People's Volunteer Army 9th Army to infiltrate the northeastern part of North Korea. On 27 November 1950, the Chinese force surprised the US X Corps commanded by Major General Edward Almond at the Chosin Reservoir area. A brutal 17-day battle in freezing weather soon followed. Between 27 November and 13 December, 30,000 United Nations Command troops under the field command of Major General Oliver P. Smith were encircled and attacked by about 120,000 Chinese troops under the command of Song Shilun, who had been ordered by Mao Zedong to destroy the UN forces.
context_section_description: Although the 1st Marine Division landed at Wonsan as part of Almond's US X Corps, Almond and Major General Oliver P. Smith of the 1st Marine Division shared a mutual loathing of each other that dated back to a meeting before the landing at Inchon, when Almond had spoken of how easy amphibious landings are even though he had never been involved in one. Smith believed there were large numbers of Chinese forces in North Korea despite the fact that higher headquarters in Tokyo said otherwise, but Almond felt Smith was overly cautious. The mutual distrust between the commanders caused Smith to slow the 1st Marine Division's advance towards the Chosin Reservoir in violation of Almond's instructions. Smith established supply points and airfields along the way at Hagaru-ri and Koto-ri.
  As the US X Corps was pushing towards the reservoir, the Chinese formulated their strategy, based on their experiences in the Chinese Civil War. Working from the assumption that only a light UN presence would be at the reservoir, the Chinese 9th Army was first to destroy the UN garrisons at Yudami-ni and Sinhung-ni, then push towards Hagaru-ri. Believing the bulk of the US X Corps would move to rescue the destroyed units, the 9th Army would then block and trap the main UN forces on the road between Hagaru-ri and Hungnam. The 9th Army initially committed eight divisions for the battle, with most of the forces concentrated at Yudami-ni and Sinhung-ni.
  The flaw in the Chinese plan was a lack of accurate intelligence about the UN forces. Even though the US X Corps was stretched thin over northeast Korea, the slow Marine advance allowed the bulk of the US 1st Marine Division, including the 5th, 7th and 11th Marines, to be concentrated at Yudami-ni. Furthermore, the strategically important Hagaru-ri, where a C-47-capable airfield was under construction and a supply dump, was not a priority for the Chinese despite being lightly defended by the 1st and 7th Marines. Only Regimental Combat Team 31 (RCT-31), an understrength and hastily formed regimental combat team of the US 7th Infantry Division, was thinly spread along the eastern bank of the reservoir. Those units would later take the brunt of the Chinese assaults. As for the UN forces, the 1st Marine Division had an effective strength of 25,473 men at the start of the battle, and it was further reinforced by the British Royal Marines unit 41 (Independent) Commando and the equivalent of two regiments from the 3rd and 7th Army Infantry Divisions. The UN forces had a combined strength of about 30,000 men during the course of the battle. The UN forces at Chosin were also supported by one of the greatest concentrations of air power during the Korean War, since the 1st Marine Aircraft Wing stationed at Yonpo Airfield and five aircraft carriers from the US Navy's Task Force 77 were able to launch 230 sorties daily to provide close air support during the battle, while the US Air Force Far East Combat Cargo Command in Japan reached the capacity of airdropping 250 tons of supplies per day to resupply the trapped UN forces.
  Although the 9th Army was one of China's elite formations, composed of veterans and former POWs from the Huaihai Campaign, several deficiencies hampered its ability during the battle. Initially the 9th Army was intended to be outfitted in Manchuria during November, but Mao suddenly ordered it into Korea before that could happen. As a result, the 9th Army had almost no winter clothing for the harsh Korean winter. Similarly, poor logistics forced the 9th Army to abandon heavy artillery, while working with little food and ammunition. The food shortage forced the 9th Army to initially station a third of its strength away from the Chosin Reservoir in reserve, and starvation and exposure broke out among the Chinese units, since foraging was not an option in the sparsely populated area. By the end of the battle, more Chinese troops had died from the cold than from combat and air raids.
  The Chinese strength is usually estimated at 120,000 troops for the battle, as the 9th Army was composed of 12 divisi
caption: Map of the Battle of the Changjin (Chosin) Reservoir.[e]
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