The Battle of Masan was an engagement between United Nations Command (UN) and North Korean forces, which took place early in the Korean War between August 5 and September 19, 1950, in the vicinity of Masan and the Naktong River in southeastern South Korea. It was part of the Battle of Pusan Perimeter, and was one of several large engagements fought simultaneously. The battle ended in a victory for the UN after large numbers of United States Army (US) troops were able to repel the repeated attacks of two Korean People's Army (KPA) divisions.
Operating as the extreme southern flank of the Pusan Perimeter, the US 25th Infantry Division placed its regiments around Masan, with the 24th Infantry Regiment and 5th Regimental Combat Team based in Haman and nearby Sobuk-san, and the 35th Infantry Regiment based along the Nam River to the west of the city. Throughout the six-week battle, the KPA 6th and 7th Divisions attacked the 25th Division's regiments in an attempt to break through the UN forces and attack Pusan.
An initial UN counteroffensive out of Masan proved ineffective in stopping the KPA from advancing. In the subsequent fight, the 35th Infantry was able to repel the KPA at the Battle of Nam River and were highly regarded for these actions. However, the 24th Infantry performed very poorly at the battles of Blue Mountain and Haman, forcing the 25th Division to muster reserves to counter the KPA gains against the 24th.
Background Outbreak of war Following the 25 June 1950 invasion of South Korea by North Korea, the United Nations decided to commit troops to the conflict on behalf of South Korea. The United States subsequently committed ground forces to the Korean peninsula with the goal of fighting back the KPA invasion and preventing South Korea from collapsing. However, US forces in the Far East had been steadily decreasing since the end of World War II, five years earlier, and at the time the closest forces were the 24th Infantry Division, headquartered in Japan. The division was understrength, and most of its equipment was antiquated due to reductions in military spending. Regardless, the 24th Division was ordered to South Korea.
The 24th Infantry Division was the first US unit sent into Korea with the mission to take the initial "shock" of KPA advances, delaying much larger KPA units to buy time to allow reinforcements to arrive. The division was alone for several weeks as it attempted to delay the KPA, making time for the 1st Cavalry and the 7th and 25th Infantry Divisions, along with other Eighth United States Army supporting units, to move into position. Advance elements of the 24th Infantry Division were badly defeated in the Battle of Osan on July 5, the first encounter with KPA forces. For the first month after that defeat, the 24th Infantry Division was repeatedly defeated and forced south by superior KPA numbers and equipment in engagements around Chochiwon, Chonan, and Pyongtaek. The division made a final stand in the Battle of Taejon, where it was nearly destroyed, but delayed KPA forces until July 20. By that time, the Eighth Army's force of combat troops were roughly equal to KPA forces attacking the region, with new UN units arriving every day.
North Korean advance With Taejon captured, KPA forces began surrounding the Pusan Perimeter in an attempt to envelop it. The KPA 4th and 6th Infantry Divisions advanced south in a wide flanking maneuver. The two divisions attempted to envelop the UN's left flank, but became extremely spread out in the process. They advanced on UN positions with armor and superior numbers, repeatedly pushing back UN forces.
US forces finally halted the KPA advance in a series of engagements in the southern section of the country. Forces of the 3rd Battalion, 29th Infantry Regiment, newly arrived in the country, were wiped out at Hadong in a coordinated ambush by KPA forces on July 27, opening a pass to the Pusan area. Soon after, KPA forces took Chinju to the west, pushing back the US 19th Infantry Regiment and leaving routes to the Pusan open for more KPA attacks. US formations were subsequently able to defeat and push back the KPA on the flank in the Battle of the Notch on August 2. Suffering mounting losses, the KPA force in the west withdrew for several days to re-equip and receive reinforcements. This granted both sides a reprieve to prepare for the attack on the Pusan Perimeter.
Battle
Task Force Kean Lieutenant General Walton Walker and the Eighth Army began preparing a counteroffensive, the first conducted by the UN in the war, for August. It would kick off with an attack by the US reserve units in the Masan area to secure Chinju from the KPA 6th Division, followed by a larger general push to the Kum River in the middle of the month. One of his goals was to break up a suspected massing of KPA troops near the Taegu area by forcing the diversion of some KPA units southward. On August 6, the Eighth Army issued the operational directive for the attack by Task Force Kean, named for the US 25th Infantry Division commander, Major General William B. Kean. Task Force Kean consisted of the 25th Division, less the 27th Infantry Regiment and a field artillery battalion, with the 5th Regimental Combat Team (5th RCT) and the 1st Provisional Marine Brigade attached. Together this represented a force of about 20,000 men. The plan of attack required the force to move west from positions held near Masan, seize the Chinju Pass, and secure the line as far as the Nam River. However, the offensive relied on the arrival of the entire 2nd Infantry Division, as well as three more battalions of American tanks.
Task Force Kean kicked off its attack on August 7, moving out from Masan. At the Notch, a northern pass into the city and site of a previous battle, the 35th Infantry Regiment encountered 500 KPA infantry, defeating them. The force surged forward to Pansong, inflicting another 350 casualties on the KPA. There, they overran the KPA 6th Division's headquarters. However the rest of the task force was slowed by KPA resistance. Task Force Kean pressed on the Chindong-ni area, resulting in a confused battle where the fragmented force had to rely on air strikes and airdrops to keep it effective. Task Force Kean'''s offensive had collided with one being delivered simultaneously by the KPA 6th Division.
Heavy fighting continued in the area for three days. By August 9, Task Force Kean was poised to retake Chinju. The task force, aided by air power, initially advanced quickly though KPA resistance was heavy. On August 10 the Marines picked up the advance, inadvertently discovering the KPA 83rd Motorized Regiment of the 105th Armored Division. F4U Corsairs from the 1st Marine Air Wing strafed the retreating column repeatedly, inflicting 200 casualties and destroying about 100 of the regiment's equipment vehicles. However the 1st Provisional Marine Brigade elements were withdrawn from the force on August 12 to be redeployed elsewhere on the perimeter. Task Force Kean continued forward supported by naval and field artillery, capturing the area around Chondong-ni. However, Eighth Army requested several of its units to redeploy to Taegu to be used elsewhere on the front, particularly at the Naktong Bulge
An attempt to move the 25th Infantry Division's division trains through the valley became mired in the mud through the night of August 10–11 and was attacked in the morning by KPA who had driven American forces from the high ground. In the confusion, KPA armor was able to penetrate roadblocks and assault the supporting artillery positions. The surprise attack was successful in wiping out most of the 555th and 90th Field Artillery Battalions, with much of their equipment. Both KPA and US armor swarmed to the scene and US Marine aviation continued to provide air cover, but neither side was able to make appreciable gains despite inflicting heavy casualties on one another. US forces were unsuccessful in retaking the positions where the artillery was overrun, suffering numerous casualties in several failed attempts to do so. Upon later inspection, the bodies of 75 men, 55 from the 555th Field Artillery and 20 from the 90th Field Artillery, were found executed when the area again came under American control, in what was later known as the Bloody Gulch massacre. Task Force Kean was forced to withdraw back to Masan, unable to hold its gains, and by August 14 it was approximately in the same positions it had been in when it started the offensive.Task Force Kean had failed in its objective of diverting North Korean troops from the north, and also failed in its objective of reaching the Chinju Pass. However, the offensive is noted to have significantly increased morale among the troops of the 25th Infantry Division, which performed extremely well in subsequent engagements. The KPA 6th Division had been reduced to 3,000–4,000 and had to replenish its ranks with South Korean conscripts from Andong. Fighting in the region continued for the rest of the month.
UN redraws battle lines Walker then ordered the US 25th Infantry Division, under Kean, to take up defensive positions on the Pusan Perimeter southern flank west of Masan. By August 15, the 25th Infantry Division had moved into these positions. Rough terrain west of Masan limited the choice of the positions. The mountain group west of Masan was the first readily defensible ground east of the Chinju Pass. The mountain ridges of Sobuk-san dominated the area and protected the Komam-ni-Haman-Chindong-ni road, the only means of north-south communication west of Masan.
Northwest of Komam-ni () was the broken spur of P'il-bong, dominated by Sibidang-san, along the Nam River. Sibidang was an excellent observation point for the surrounding area, and US artillery emplaced in the Komam-ni area could interdict the road junction at Chungam-ni. The US 35th Infantry Regiment set up positions at Sibidang-Komam-ni, in the northern part of the 25th Infantry Division defense line. The 35th Regiment line extended from a point west of Komam-ni to the Nam River and then turned east along that stream to its confluence with the Naktong River. It was a long regimental line, about , twice the length a regiment was typically assigned.
The 1st Battalion, 35th Infantry held the regiment's left flank west of Komam-ni, while the 2nd Battalion held the right along the Nam River. 3rd Battalion, redesignated from the 1st Battalion, 29th Infantry Regiment, was in reserve on the road south of Chirwon from where it could move quickly to any part of the line. To the south was the US 24th Infantry Regiment and west of Chindong-ni, the 5th Regimental Combat Team was on the division's left flank. On division orders, the 5th Regimental Combat Team first held the ground above the Chindong-ni coastal road only as far as Yaban-san. Kean soon decided, however, that the 5th RCT should close the gap northward between it and the 24th Infantry. When the 5th RCT sent a SROK unit of 100 men under American officers to the higher slope of Sobuk-san, KPA troops already there drove them back. Kean then ordered the 5th RCT to take this ground, but it was too late.
North Korean consolidation