At dawn on Sunday, June 25, 1950, the North Korean People’s Army (KPA) crossed the 38th parallel behind artillery fire. The KPA justified its assault with the claim that Republic of Korean (ROK) troops attacked first and that the KPA were aiming to arrest and execute the “bandit traitor” Syngman Rhee.  The fighting began on the strategic Ongjin Peninsula in the northwestern area of Korea, approximately 80 miles northwest of Seoul, South Korea.  

Shortly after the fighting began, the KPA forces attacked all along the 38th parallel. The North Koreans had a combined arms force including tanks supported by heavy artillery. The ROK had no tanks, anti-tank weapons or heavy artillery to stop such an attack. In addition, South Koreans committed their forces in a piecemeal fashion and these were routed in a few days. 

On June 27, 1950, Syngman Rhee evacuated from Seoul with some of the government. On June 28, 1950, at 2 am, the South Korean Army blew up the Hangang Bridge, across the Han River, north of Seoul, in an attempt to stop the North Korean army. The bridge was detonated while 4,000 refugees were crossing and hundreds were killed. Destroying the bridge also trapped many South Korean military units north of the Han River. In spite of such desperate measures, Seoul was occupied by the KPA on June 28, 1950. 

A number of South Korean National Assemblymen remained in Seoul when it fell, and forty-eight subsequently pledged allegiance to the government of North Korea. 

On June 28, 1950, the exiled Syngman Rhee ordered the massacre of suspected political opponents in his own country. 

By June 30, 1950, the ROK military forces, which numbered 95,000 personnel on June 25th, were reduced to less than 22,000 men. In early July, 1950, United States military forces landed in South Korea, and the remaining ROK military personnel were placed under U.S. Operational Command, as part of the United Nations Operational Command.


 As soon as word of the attack by the KPA was received, U.S. Secretary of State Dean Acheson informed President Truman that the North Koreans had invaded South Korea. Truman and Acheson discussed a U.S. invasion response and agreed that the United States was obligated to act, paralleling the North Korean invasion with Germany’s aggressions in the 1930s, and with the conclusion being that the mistake of appeasement must not be repeated.

 The President Harry Truman administration was unprepared for the invasion. Korea was not included in the strategic Asian Defense Perimeter outlined by Secretary of State Dean Acheson. Truman himself was at his home in Independence, Missouri.  Military strategists were more concerned with the security of Europe against the Soviet Union than East Asia. At the same time, the Truman administration was worried that a war in Korea could quickly widen into another world war, should the Chinese or Soviets decide to get involved.

 Several U.S. industries were mobilized to supply materials, labor, capital, production facilities, and other services necessary to support the military objectives of the Korean War.

 While there was initial hesitance by some in the US government to get involved in the war, considerations about Japan played a part in the ultimate decision to engage on behalf of South Korea. Especially after the fall of China to the Communists, U.S. experts on East Asia saw Japan as the critical counterweight to the Soviet Union and China in the region. While there was no United States policy dealing with South Korea directly as a national interest, its proximity to Japan increased the importance of South Korea. Essentially, the American response to the North Korean attack stemmed from considerations of U.S. policy toward Japan.

 Another major consideration was the possible Soviet reaction in the event that the U.S. intervened. The Truman administration was fearful that a war in Korea was a diversionary assault that would escalate to a general war in Europe, once the United States committed in Korea.

 The UN Security Council approved the use of force to help the South Koreans, and the U.S. immediately began deploying available air and naval forces that were in the area to South Korea.  The Truman administration still refrained from committing on the ground because some advisers believed the North Koreans could be stopped by air and naval power alone.

 The Truman administration was still uncertain if the attack was a ploy by the Soviet Union, or just a test of U.S. resolve. The decision to commit ground troops became viable when a communiqué was received on June 27, 1950, indicating that the Soviet Union would not move against U.S. forces in Korea. The Truman administration now believed it could intervene in Korea without undermining its commitments elsewhere.

 President Truman later acknowledged that he believed fighting the invasion was essential to the U.S. goal of the global containment of communism

 On June 25, 1950, the United Nations Security Council unanimously condemned the North Korean invasion of the Republic of Korea.  After debating the matter, the Security Council, on June 27, 1950, published Resolution 83, which recommended that United Nations member states provide military assistance to the Republic of Korea.


 On June 27, 1950, President Truman ordered U.S. air and sea forces to help the South Korean regime.

 In August 1950, the President and the Secretary of State obtained the consent of Congress to appropriate $12 billion for military action in Korea.   

 Because of the extensive defense cuts and the emphasis placed on building a nuclear bomber force; none of the services were in a position to make a robust response with conventional military strength. General Omar Bradley, Chairman of the United States Joint Chiefs of Staff, was faced with re-organizing and deploying a U.S. military force that was a shadow of its World War II counterpart.

 Acting on Secretary of State Acheson’s recommendation, President Truman ordered General Douglas MacArthur to transfer material to the South Korean military, while giving air cover to the evacuation of U.S. nationals. President Truman disagreed with his advisers who recommended unilateral U.S. bombing of the North Korean forces, and ordered the U. S. Navy Seventh Fleet to protect the Republic of China (Taiwan); whose government asked to fight in Korea. The United States denied Republic of China’s (ROC) request for combat, lest it provoke a communist Chinese retaliation.

 Because the United States had sent the Seventh Fleet to “neutralize” the Taiwan Strait between Taiwan and China, Chinese Premier Zhou Enlai criticized both the United Nations and the United States initiatives as “armed aggression on Chinese territory”.

 The first significant U.S. engagement of the Korean War was the Battle of Osan, which involved the 540-soldier Task Force Smith; a part of the small forward element of the U. S. 24th Infantry Division, which had previously been stationed in Japan. On July 5, 1950, Task Force Smith attacked the North Koreans at Osan.  The attack was staged without weapons capable of destroying the North Koreans’ tanks. Task Force Smith was unsuccessful and the result was 180 dead, wounded, or taken prisoner. The KPA progressed southwards, pushing back the U.S. force at Pyongtaek, Chonan, and Chochiwon: forcing the 24th Division’s retreat to Taejeon, which the KPA captured in the Battle of Taejon.  The 24th Division suffered 3,602 dead and wounded and 2,962 captured, including its commander, Major General William F. Dean.

 By August 1950, the KPA had steadily pushed the ROK Army and the U. S. Eight Army southwards. The impacts of the Truman administration’s defense budget cutbacks were now keenly felt.  As U.S. troops fought a series of costly rearguard actions. Lacking sufficient anti-tank weapons, artillery or armor, they were driven down the Korean Peninsula. During their advance, the KPA purged the Republic of Korea’s intelligentsia by killing civil servants and intellectuals. On August 20, 1950, General MacArthur warned North Korean leader Kim Il-sung he was responsible for the KPA’s atrocities.


 By September 1950, UN forces were hemmed into a small corner of southeast Korea, near Pusan. This 140-mile perimeter enclosed about 10% of Korea, in a line partially defined by the Nakdong River.

 Although North Korea’s early successes led them to predict they would end the war by the end of August 1950, Chinese leaders were more pessimistic. To counter a possible U.S. deployment, Zhou Enlai secured a Soviet commitment to have the Soviet Union support Chinese forces with air cover, and deployed 260,000 soldiers along the Korean border, under the command of Chinese Communist Party Leader Gao Gang.  

 During the Battle of the Pusan Perimeter (August–September 1950); the U.S. Army withstood KPA attacks meant to capture Pusan at the Naktong Bulge, P’shang-dong and Taegu.

 The United States Air Force (USAF) interrupted KPA logistics with 40 daily ground support missions that destroyed 32 bridges, halting most daytime road and rail traffic. KPA forces were forced to hide in tunnels by day and move only at night.  To deny material to the KPA, the USAF destroyed logistics depots, petroleum refineries, and harbors, while the U.S. Navy air forces attacked transport hubs. Consequently, the over-extended KPA could not be supplied throughout the south.

 In the meantime, U.S. garrisons in Japan continually dispatched soldiers and material to reinforce defenders in the Pusan Perimeter. Tank battalions were directly deployed to Korea, from the U.S. mainland to the port of Pusan, the largest Korean port. By late August 1950, the Pusan Perimeter had some 500 medium tanks battle-ready. In early September 1950, ROK Army and UN Command forces outnumbered the KPA 180,000 to 100,000 soldiers.

 Against the rested and re-armed Pusan Perimeter defenders and their reinforcements; the KPA were undermanned and poorly supplied.  Unlike the UN Command, they lacked naval and air support.

 To relieve the Pusan Perimeter, General MacArthur recommended an amphibious landing at Incheon, near Seoul, and well over 100 miles behind the KPA lines.


On July 6, July, he ordered Major General Hobart R. Gay, Commander of the 1st Cavalry Division, to plan a division’s amphibious landing at Incheon.  On July 12–14, 1950, the 1st Cavalry Division embarked from Japan, to reinforce the 24th Infantry Division inside the Pusan Perimeter.

 The Incheon Landing was a combined U.S. Army, U.S. Marine Corps, and ROK Army action. The X Corps, was led by U. S. Army Major General Edward Almond, and consisted of 40,000 men of the 1st Marine Division, the 7th Infantry Division, and ROK Army soldiers.

 The Incheon Landing occurred on September 15, 1950, and the amphibious assault force faced few KPA defenders at Incheon: military intelligence, psychological warfare, guerrilla, reconnaissance; and protracted bombardment facilitated a relatively light battle.

 On September 25, 1950, Seoul was recaptured by South Korean forces. U.S raids caused heavy damage to the KPA, destroying its tanks and artillery.  The X Corps rapidly defeated the KPA defenders around Seoul, thus threatening to trap the main KPA force in Southern Korea.


After the Incheon Landing, the 1st Cavalry Division began its northward advance from the Pusan Perimeter. “Task Force Lynch” (after Lieutenant Colonel James H. Lynch), 3rd Battalion, 7th Cavalry Regiment, and two 70th Tank Battalion units (Charlie Company and the Intelligence–Reconnaissance Platoon) effected the “Pusan Perimeter Breakout” through 106 miles of enemy territory to join the 7th Infantry Division at Osan.

North Korean troops in the south, instead of effectively withdrawing north, rapidly disintegrated, leaving Pyongyang vulnerable. During the general retreat only 25,000 to 30,000 North Korean soldiers managed to reach the KPA lines. 

 On September 27, 1950, General MacArthur received the top secret National Security Council Memorandum 81/1 from the Truman administration reminding him that operations north of the 38th parallel were authorized only if;

 “…at the time of such operation there was no entry into North Korea by major Soviet or Chinese Communist forces, no announcements of intended entry, nor a threat to counter our operations militarily”.

 On September 29, 1950, MacArthur restored the government of the Republic of Korea under Syngman Rhee.

 On September 30 1950 Chinese Premier Zhou Enlai warned the United States that China was prepared to intervene in Korea if the United States crossed the 38th parallel. Zhou attempted to advise North Korean commanders on how to conduct a general withdrawal by using the same tactics that allowed Chinese communist forces to successfully escape Chiang Kai-shek’s Encirclement Campaigns in the 1930s; but by some accounts North Korean commanders did not use these tactics effectively.


 By October 1, 1950, the UN Command repelled the KPA northwards past the 38th parallel, and the ROK Army crossed after them, into North Korea.

  MacArthur made a statement demanding the KPA’s unconditional surrender.  Six days later, on October 7th, with UN authorization, the UN Command forces followed the ROK forces northwards. The X Corps landed at Wonsan (in southeastern North Korea) and Riwon (in northeastern North Korea). The Eighth U.S. Army and the ROK Army drove up western Korea and captured Pyongyang, the Korean capital, on October 19, 1950.

The 187th Airborne Regimental Combat Team made their first of two combat jumps during the Korean War on October 20 1950 at Sunchon and Sukchon.

 The missions of the 187th were to cut the road north going to China, preventing North Korean leaders from escaping from Pyongyang; and to rescue U.S. Prisoners of War. At month’s end, UN forces held 135,000 KPA prisoners of war. As they neared the Sino-Korean border, the UN forces in the west were divided from those in the east by 50–100 miles of mountainous terrain.

 By taking advantage of the UN Command’s strategic momentum against the communists; General MacArthur believed it necessary to extend the Korean War into China to destroy depots supplying the North Korean war effort. President Truman disagreed, and ordered caution at the Sino-Korean border.

 On 20 August 1950, Premier Zhou Enlai informed the UN that:

 Korea is China’s neighbor … The Chinese people cannot but be concerned about a solution of the Korean question”.

 Thusly, through neutral-country diplomats, China warned that in safeguarding Chinese national security, they would intervene against the UN Command in Korea.  President Truman interpreted the communication as “a bald attempt to blackmail the UN”, and dismissed the warning.

 On October 1, 1950, the day that UN troops crossed the 38th parallel, the Soviet ambassador forwarded a telegram from Stalin to Mao and Zhou requesting that China send five to six divisions into Korea, and Kim Il-sung sent frantic appeals to Mao for Chinese military intervention. At the same time, Stalin made it clear that Soviet forces themselves would not directly intervene.

 In a series of emergency meetings that lasted from October 2nd through October 5th, 1950, Chinese leaders debated whether to send Chinese troops into Korea. There was considerable resistance among many leaders, including senior military leaders, to confronting the U.S. in Korea.

 On October 18, 1950, Zhou Enlai ordered two hundred thousand Chinese troops to enter North Korea; which they did on October 25th.

 United Nations aerial reconnaissance had difficulty sighting the Chinese troop units in daytime, because their marching and bivouac discipline minimized aerial detection. The Chinese troops marched “dark-to-dark”, and aerial camouflage (concealing soldiers, pack animals, and equipment) was deployed by 5:30 AM.

 Meanwhile, daylight advance parties scouted for the next bivouac site. During daylight activity or marching, soldiers were to remain motionless if an aircraft appeared, until it flew away.

 On October 15, 1950, President Truman and General MacArthur met at Wake Island in the mid-Pacific Ocean. To President Truman, MacArthur speculated there was little risk of Chinese intervention in Korea, and that the Chinese Army’s opportunity for aiding the KPA had lapsed. He believed the Chinese Army had 300,000 soldiers in Manchuria and 100,000–125,000 soldiers at the Yalu River.


 After secretly crossing the Yalu River on October 19, 1950, the Chinese troops 13th Army Group launched the First Phase Offensive on October 25, 1950, attacking the advancing UN forces near the Sino-Korean border. This military decision made solely by China changed the attitude of the Soviet Union. Twelve days after Chinese troops entered the war, Stalin allowed the Soviet Air Force to provide air cover, and supported more aid to China.

 After inflicting heavy losses on the ROK II Corps at the Battle of Onjong, the first confrontation between Chinese and U.S. military occurred on November 1, 1950. Deep in North Korea, thousands of soldiers from the Chinese 39th Army encircled and attacked the U.S. 8th Cavalry Regiment with three-prong assaults—from the north, northwest, and west—and overran the defensive position flanks in the Battle of Unsan. The surprise assault resulted in the UN forces retreating back to the Ch’ongch’on River; while the Chinese unexpectedly disappeared into mountain hideouts following victory. It is unclear why the Chinese did not press the attack and follow up their victory.

 The UN Command, however, was unconvinced that the Chinese had openly intervened because of the sudden Chinese withdrawal. On November 24, 1950, the “Home-by-Christmas Offensive was launched with the U.S. Eighth Army advancing in northwest Korea, while the US X Corps attacked along the Korean east coast.

 The Chinese troops were waiting in ambush with their Second Phase Offensive, which they executed at two sectors: in the East at the Chosin Reservoir and in the Western sector at Ch’ongch’on River.

 On November 25, 1950, at the Korean western front, the Chinese 13th Army Group attacked and overran the ROK II Corps at the Battle of the Ch’ongch’on River, and then inflicted heavy losses on the U.S. 2nd Infantry Division on the UN forces’ right flank. By November 30, 1950, the Chinese 13th Army Group managed to expel the U.S. Eighth Army from northwest Korea; retreating from the north faster than they had advanced.

  Concurrent with the Battle of the Ch’ongch’on River was the Battle of the Chosin Reservoir, which the Chinese 9th Army Group initiated on November 27, 1950.

 The surprise attack also forced X Corps to retreat from northeast Korea, but they were in the process able to breakout from the attempted encirclement by the Chinese and execute a successful tactical withdrawal.

 X Corps managed to establish a defensive perimeter at the port city of Hungnam on December 11th and were able to evacuate by December 24th, in order to reinforce the badly depleted U.S. Eighth Army to the south.

 China justified its entry into the war as a response to “American aggression in the guise of the UN”.

 Later, the Chinese claimed that U.S. bombers had violated the People’s Republic of China national airspace on three separate occasions and attacked Chinese targets before China intervened.


With Lieutenant General Matthew Ridgway assuming the command of the U.S. Eighth Army on December 26, 1950, the Chinese Army and the KPA launched their Third Phase Offensive (also known as the “Chinese New Year’s Offensive”) on New Year’s Eve of 1950/51.

 Utilizing night attacks in which UN Command fighting positions were encircled and then assaulted by numerically superior troops who had the element of surprise, the attacks were accompanied by loud trumpets and gongs, which fulfilled the double purpose of facilitating tactical communication and mentally disorienting the enemy. UN forces initially had no familiarity with this tactic, and as a result some soldiers panicked, abandoning their weapons and retreating to the south. The Chinese New Year’s Offensive overwhelmed United Nation’s military forces.  This resulted in allowing the Chinese and KPA to occupy Seoul for the second time on January 4, 1951.

 These setbacks prompted General MacArthur to consider using nuclear weapons against the Chinese or North Korean interiors, with the intention that radioactive fallout zones would interrupt the Chinese supply chains. However, upon the arrival of the charismatic General Ridgway, the esprit de corps of the bloodied Eighth Army immediately began to revive.

 UN forces retreated to Suwon in the west, Wonju in the center, and the territory north of Samcheck in the east; where the battlefront stabilized and held. The Chinese Army had outrun its logistics capability and thus was unable to press on beyond Seoul as food, ammunition, and material were carried nightly, on foot and bicycle, from the border at the Yalu River to the three battle lines.

 In late January, upon finding that the Chinese Army and the KPA had abandoned their battle lines, General Ridgway ordered a reconnaissance-in-force, which became Operation Roundup (February 5, 1951).  A full-scale X Corps advance proceeded, which fully exploited the UN Command’s air superiority, concluding with the United Nation’s troops reaching the Han River and recapturing Wonju.

 In early February 1951, the South Korean 11th Division initiated the operation to destroy the guerrillas and their sympathizer citizens in South Korea.

 In mid-February, the Chinese Army counterattacked with the Fourth Phase Offensive and achieved initial victory at Hoengseong. But the offensive was soon blunted by the IX Corps positions at Chipyong-ni in the center.  The U. S. 2nd Infantry “Warrior” Division’s 23rd Regimental Combat Team and a French Infantry Battalion fought a short but desperate battle that broke the attack’s momentum.

 In the last two weeks of February 1951, Operation Roundup was followed by Operation Killer; carried out by the revitalized Eighth Army. It was a full-scale, battlefront-length attack staged for maximum exploitation of firepower to kill as many KPA and Chinese troops as possible. Operation Killer concluded with I Corps re-occupying the territory south of the Han River, and IX Corps capturing Hoengseong.

 On March 7, 1951, the Eighth Army attacked with Operation Ripper, expelling the Chinese troops and the KPA from Seoul on March 14, 1951. This was the fourth conquest of the city in a year’s time, leaving it a ruin; the 1.5 million pre-war populations were down to 200,000, and people were suffering from severe food shortages.

 On April 11, 1951, Commander-in-Chief Harry Truman relieved the controversial General Douglas MacArthur, Supreme Commander in Korea.

 There were several reasons for the dismissal. MacArthur crossed the 38th parallel in the mistaken belief that the Chinese would not enter the war, leading to major allied losses. He believed that whether to use nuclear weapons should be his decision, not the president’s. MacArthur also threatened to destroy China unless it surrendered.

 While MacArthur felt total victory was the only honorable outcome; Truman was more pessimistic about his options involved in a land war in Asia, and felt a truce and orderly withdrawal from Korea could be a valid solution.


General Matthew Ridgway was appointed Supreme Commander in Korea, and he regrouped the UN forces for successful counterattacks, while General James Van Fleet assumed command of the U.S. Eighth Army.

 Further attacks slowly depleted the Chinese and KPA forces; Operations Courageous (March 23–28, 1951) and Tomahawk (March 23, 1951) were a joint ground and airborne infiltration meant to trap Chinese forces between Kaesong and Seoul. UN forces advanced to “Line Kansas”, north of the 38th parallel

.The second of two combat jumps by the 187th Airborne Regimental Combat Team (“Rakkasans”) was on Easter Sunday 1951, at Munsan-ni, South Korea, codenamed Operation Tomahawk. The mission was to get behind Chinese forces and block their movement north.

 The Chinese counterattacked in April 1951, with the Fifth Phase Offensive, also known as the Chinese Spring Offensive, with three field armies (approximately 700,000 men). The first thrust of the offensive fell upon I Corps; which fiercely resisted in the Battle of the Imjin River (April 22–25 1951) and the Battle of Kapyong (April 22–25 1951).  I Corps blunted the impetus of the offensive, which was halted at the “No-name Line” north of Seoul.

 On May 15, 1951, the Chinese commenced the second impulse of the Spring Offensive and attacked the ROK Army and the U.S. X Corps in the east at the Soyang River. After initial success, they were halted by 20 May.


At month’s end, the U.S. Eighth Army counterattacked and regained “Line Kansas”, just north of the 38th parallel. The UN’s “Line Kansas” halt and subsequent offensive action stand-down; began the stalemate that lasted until the armistice of 1953.

 For the remainder of the Korean War, the UN Command and the Chinese Army and the North Korea Army fought but exchanged little territory, as the stalemate held. Large-scale bombing of North Korea continued, and protracted armistice negotiations began 10 July 1951 at Kaesong.

 Combat continued while the belligerents negotiated; the goal of the UN Command forces was to recapture all of South Korea and to avoid losing territory.

 The Chinese and the KPA attempted similar operations, and later effected military and psychological operations in order to test the UN Command’s resolve to continue the war.

 The principal battles of the stalemate include:

Battle of Bloody Ridge (August 18 – September 15, 1951)

Battle of the Punchbowl (31 August – September   21, 1951)

Battle of Heartbreak Ridge (September 13 – October 15, 1951)

Battle of Old Baldy (June 26 – August 4, 1952)

Battle of White Horse (October 6–15 1952)

Battle of Triangle Hill (October 14 – November 25, 1952)

Battle of Hill Eerie (March 21 – June 21, 1952)

Siege of Outpost Harry (June 10–18, 1953)

Battle of the Hook (May 28–29, 1953)

Battle of Pork Chop Hill (March 23 – July 16, 1953)

Battle of Kumsong (July 13–27, 1953)

 Chinese troops suffered from deficient military equipment, serious logistical problems, overextended communication and supply lines, and the constant threat of United Nations bombers. All of these factors generally led to a rate of Chinese casualties that was far greater than the casualties suffered by UN troops.

 The on-again, off-again armistice negotiations continued for two years; first at Kaesong, on the border between North and South Korea, and then at the neighboring village of Panmunjom.

 A major, problematic negotiation point was prisoner of war (POW) repatriation. The Chinese, the North Koreans and the UN Command could not agree on a system of repatriation because many Chinese and North Korean soldiers refused to be repatriated back to the north; which was unacceptable to the Chinese and North Koreans.


In the final armistice agreement, signed on July 27, 1953, a Neutral Nations Repatriation Commission, under the chairman Indian General K. S. Thimayya, was set up to handle the matter.

 On November 29, 1952, president-elect, Dwight D. Eisenhower, went to Korea to learn what might end the Korean War. With the United Nations’ acceptance of India’s proposed Korean War Armistice, the North Koreans, the Chinese, and the UN Command ceased fire with the battle line approximately at the 38th parallel.

 Upon agreeing to the armistice, the belligerents established the Korean Demilitarized Zone (DMZ), which has since been patrolled by the North Koreans, the South Koreans, the U. S. Army, and Joint United Nations Commands.

 The Demilitarized Zone runs northeast of the 38th parallel; to the south, it travels west. The old Korean capital city of Kaesong, site of the armistice negotiations, originally was in pre-war South Korea, but now is part of North Korea.

 After the war, Operation Glory was conducted from July to November 1954, to allow combatant countries to exchange their dead.

 The remains of 4,167 U.S. Army and U.S. Marine Corps dead were exchanged for 13,528 KPA and PVA dead, and 546 civilians dead in UN prisoner-of-war camps were delivered to the South Korean government.

 According to the data from the U.S. Department of Defense; the United States suffered 33,686 battle deaths, along with 2,830 non-battle deaths, during the Korean War.