Defensive position On August 1, the Eighth Army issued an operational directive to all UN ground forces in Korea for their planned withdrawal east of the Naktong River. UN units would then establish a
Main line of resistance behind what was to be called the Busan Perimeter. The intent was to draw the line on retreating and hold off the KPA while the UN built up its forces and launched a counteroffensive. The US 25th Infantry Division held the southernmost flank at
Masan, while the 24th Infantry Division withdrew from
Geochang County to Changyeong. The 1st Cavalry Division withdrew to Waegwan. US forces demolished all bridges over the Naktong River in the retreat. At one bridge in the 1st Cavalry Division sector, the division commander attempted several times to clear refugees from the bridge but they continued to cross it despite warnings and several attempts to clear the bridge. Eventually the commander was forced to demolish the bridge, taking several hundred refugees with it. Central to the UN defensive plan was to hold the port of Busan, where vital ground supplies and reinforcements were arriving from Japan and the US. Busan possessed airfields where US combat and cargo aircraft were streaming into Korea with more supplies. A system similar to the
Red Ball Express in World War II was employed to get supplies from Busan to the front lines. Hundreds of ships arrived in Busan each month, starting with 230 in July and increasing steadily thereafter. On July 24, the UN established its highest command under MacArthur in
Tokyo, Japan. KPA forces in the meantime were suffering from overextended supply lines which severely reduced their fighting capacity. KPA forces had four possible routes in the perimeter: to the south, the pass through the city of Masan around the confluence of the Nam and Naktong rivers; another southerly route through the
Naktong Bulge and into the railroad lines at
Miryang; through the route into Daegu in the north; and through
Kyongju in the eastern corridor. The KPA mounted a large offensive in August, simultaneously attacking all four entries into the perimeter. As a result, the Battle of Busan Perimeter was not one single engagement, but a series of large battles fought between the UN and KPA divisions all along the perimeter.
UN Counteroffensive The Eighth Army, commanded by
Lieutenant General Walton Walker, 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 on the Masan area to secure Chinju, followed by a larger general push to the
Geum River in the middle of the month. One of Walker's goals was to break up a suspected massing of KPA troops near the Daegu 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,
William B. Kean. Task Force Kean consisted of the 25th Division, less the
27th Infantry Regiment and a field artillery battalion, plus the
5th Regimental Combat Team and the
1st Provisional Marine Brigade attached—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 launched its attack on August 7, moving out from Masan, but Kean's attack resulted in a
meeting engagement with one being simultaneously delivered by the KPA. Heavy fighting continued in the area for three days. By August 9, Task Force Kean was poised to retake Chinju. The Americans initially advanced quickly though heavy KPA resistance. On August 10, the Marines picked up the advance. However, the 1st Provisional Marine Brigade was withdrawn from the force on August 12 to be redeployed elsewhere on the perimeter. Task Force Kean continued forward, capturing the area around Chondong-ni. 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 forces who had driven American forces from the high ground. In the confusion, KPA armor was able to penetrate roadblocks and assault the supporting US 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 American armor swarmed to the scene and US Marine aircraft continued to provide cover, but neither side was able to make appreciable gains despite inflicting massive numbers of casualties on one another. 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. Task Force Kean was forced to withdraw back to Masan, unable to hold its gains, and by August 14 it was in approximately the same position it had been in when it started the offensive. Task Force Kean had failed in its objective of diverting KPA troops from the north, and also failed in its objective of reaching the Chinju Pass. However, the offensive was considered 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.
Naktong Bulge About north of the confluence of the Naktong and Nam rivers, the Naktong curves westward opposite
Yongsan in a wide semicircular loop. For most of this span, the Naktong river is around wide and deep, allowing infantry to wade across with some difficulty, but preventing vehicles from crossing without assistance. This perimeter was manned by a network of observation posts on the high ground where forces from the 24th Infantry Division monitored the river area. Forces in reserve would counterattack any attempted crossings by KPA forces. The division was spread extremely thinly; already understrength, it presented a very weak line.
North Korean crossing On the night of August 5–6, 800 KPA soldiers began wading across the river at the Ohang ferry site, south of Pugong-ni and west of Yongsan, carrying light weapons and supplies over their heads or on rafts. A second force attempted to cross the river further north but met with resistance and fell back. On the morning of August 6, the KPA attacked in an attempt to penetrate the lines to Yongsan. This caught the Americans, who were expecting an attack from further north, by surprise and drove them back, and the KPA captured a large amount of American equipment. The attack threatened to split the American lines and disrupt supply lines to the north. Despite American counterattacks, the KPA were able to continue pressing forward and take Cloverleaf Hill and Oblong-ni Ridge, critical terrain astride the main road in the bulge area. By August 10 the entire KPA 4th Division was across the river and beginning to move south, outflanking the American lines. The next day, scattered KPA elements attacked Yongsan. The KPA forces repeatedly attacked US lines at night, when American soldiers were resting and had greater difficulty resisting.
North Korean defeat The 1st Marine Provisional Brigade, in conjunction with Task Force Hill, mounted a massive offensive on Cloverleaf Hill and Obong-ni on August 17. At first tenacious KPA defense halted the marines' push. The KPA then mounted a counterattack following this in hopes of pushing the marines back, but this failed disastrously. By nightfall on August 18, the KPA 4th Division had been nearly annihilated and Obong-ni and Cloverleaf Hill had been retaken by US forces. The next day, the remains of the 4th Division withdrew completely across the river. In their hasty retreat, they left a large number of artillery pieces and equipment behind which the Americans used.
Eastern corridor The terrain along the ROK front on the eastern corridor made movement extremely difficult. A major road ran from Daegu east, to P'ohang-dong on Korea's east coast. The only major north–south road intersecting this line moved south from Andong through
Yongch'on, midway between Daegu and P'ohang-dong. The only other natural entry through the line was at the town of
An'gang-ni, west of P'ohang-dong, situated near a valley through the natural rugged terrain to the major rail hub of Kyongju, which was a staging post for moving supplies to Daegu. Walker chose not to heavily reinforce the area as he felt the terrain made meaningful attack impossible, preferring to respond to attack with reinforcements from the transportation routes and air cover from
Yongil Airfield, which was south of P'ohang-dong.
Triple offensive In early August, three KPA divisions mounted offensives against the three passes through the area, with the 8th Division attacking Yongch'on, 12th Division attacking P'ohang-dong and 5th Division, in conjunction with the 766th Independent Infantry Regiment, attacking An'gang-ni. The 8th Division drove for Yongch'on from
Uiseong, but its attack failed to reach the Taegu-P'ohang corridor after being surprised and outflanked by the ROK 8th Division. This fighting was so heavy that the KPA 8th Division was forced to hold its ground for a week before trying to advance. Stalled again by ROK resistance, it halted to wait for reinforcements. However the other two attacks were more successful, catching the UN forces by surprise. East of the KPA and ROK 8th Divisions, the KPA 12th Division crossed the Naktong River at Andong, moving through the mountains in small groups to reach P'ohang-dong. UN planners had not anticipated that the 12th Division would be able to cross the river effectively, and thus were unprepared. In the meantime, the ROK 3rd Division was heavily engaged with the KPA 5th Division along the coastal road to P'ohang-dong. The divisions' clashes centered on the town of Yongdok, with each side capturing and recapturing the town several times. On August 5, the KPA attacked, again taking the town from the ROK and pushing them south. On August 6, the ROK launched a counteroffensive to retake the town. However, KPA 5th Division forces were able to infiltrate the coastal road south of Yongdok at Hunghae. This effectively surrounded the ROK 3rd Division, trapping it several miles above P'ohang-dong. The KPA 766th Independent Regiment advanced around the ROK 3rd Division and took the area around P'ohang-dong. On August 10, the Eighth Army organized Task Force P'ohang—the
ROK 17th, 25th, and 26th regiments as well as the ROK 1st Anti-Guerrilla Battalion, Marine Battalion and a battery from the US
18th Field Artillery Regiment. This task force was given the mission to clear out KPA forces in the mountainous region. At the same time, Eighth Army formed Task Force Bradley under Brigadier General
Joseph S. Bradley, consisting of elements of the
8th Infantry Regiment, 2nd Infantry Division. Task Force Bradley was tasked with defending P'ohang-dong. What followed was a complicated series of fights throughout the region around P'ohang-dong and An'gang-ni as ROK forces, aided by US air forces, engaged groups of KPA in the area. The KPA 12th Division was operating in the valley west of P'ohang-dong and was able to push back Task Force P'ohang and the ROK Capital Division, which was along the line to the east. At the same time, the KPA 766th Infantry Regiment and elements of the KPA 5th Division fought Task Force Bradley at and south of P'ohang-dong. US naval fire drove the KPA troops from the town, but it became a bitterly contested
no man's land as fighting moved to the surrounding hills.
Fight for P'ohang-dong By August 13, KPA troops were operating in the mountains west and southwest of Yongil Airfield. USAF commanders, wary of KPA attacks, evacuated the
39th Fighter Squadron and
40th Fighter Squadron from the airstrip, against the wishes of General MacArthur. In the event, the airstrip remained under the protection of UN ground forces and never came under direct fire. The squadrons were moved to
Tsuiki Air Field on the island of
Kyushu, Japan. In the meantime, the ROK 3rd Division, surrounded earlier in the month, was forced farther south to the village of Changsa-dong, where US Navy craft amphibiously withdrew the division. The division would sail south to Yongil Bay to join the other UN forces in a coordinated attack to push the KPA out of the region. This evacuation was carried out on the night of August 16. By August 14, large KPA forces were focused entirely on taking P'ohang-dong. However, they were unable to hold it because of US air superiority and naval bombardment on the town. The KPA supply chain had completely broken down and more food, ammunition, and supplies were not available. UN forces began their final counteroffensive against the stalled KPA forces on August 15. Intense fighting around P'ohang-dong ensued for several days as each side suffered large numbers of casualties in back-and-forth battles. By August 17, UN forces were able to push KPA troops out of the Kyongju and An'gang-ni areas, putting the supply road to Taegu out of immediate danger. By August 19 the KPA forces had completely withdrawn from the offensive.
Daegu Shortly before the Busan Perimeter battles began, Walker established Daegu as the Eighth Army's headquarters. Right at the center of the Busan Perimeter, Daegu stood at the entrance to the Naktong River valley, an area where KPA forces could advance in large numbers in close support. The natural barriers provided by the Naktong River to the south and the mountainous terrain to the north converged around Daegu, which was also the major transportation hub and last major South Korean city aside from Busan itself to remain in UN hands. From south to north, the city was defended by the US 1st Cavalry Division, and the ROK 1st and 6th divisions of ROK II Corps. 1st Cavalry Division was spread out along a long line along the Naktong River to the south, with its
5th and
8th cavalry regiments holding a line along the river and the
7th Cavalry Regiment in reserve along with artillery forces, ready to reinforce anywhere a crossing could be attempted.
Daegu advance Five KPA divisions amassed to oppose the UN at Taegu; from south to north, the
10th, 3rd, 15th, 13th, and 1st Divisions occupied a line from Tuksong-dong and around Waegwan to Kunwi. The KPA planned to use the natural corridor of the Naktong valley from
Sangju to Daegu as their main axis of attack for the next push south. Elements of the 105th Armored Division were also supporting the attack. By August 7, the KPA 13th Division had crossed the Naktong River at Naktong-ni, northwest of Daegu. ROK troops attacked the 13th Division immediately after it completed its crossing, forcing the KPA troops to scatter into the mountains. The division reassembled to the east and launched a concerted night attack, broke the ROK defenses, and began an advance that carried it southeast of Naktong-ni on the main road to Taegu. Within a week, the KPA 1st and 13th divisions were converging on the Tabu-dong area, about north of Daegu. During August 12–16, the KPA 15th Division formed up on the east side of the Naktong River in the vicinity of Yuhak-san, northwest of Tabu-dong. It was quickly locked in combat on Yuhak-san with the ROK 1st Division.
Triangulation Hill South of Waegwan, two more KPA divisions stood ready to cross the Naktong River in a coordinated attack with the divisions to the north. The experienced KPA 3rd Division was concentrated in the vicinity of
Songju, while the untested KPA 10th Division was concentrated in the
Koryong area. These two divisions crossed in the US 1st Cavalry Division's line. The KPA 3rd Division's 7th Regiment started crossing the Naktong on August 9. Despite being spotted and taking fire, the bulk of it reached the east bank safely and moved inland into the hills. The 5th Cavalry Regiment and its supporting artillery, now fully alerted, spotted the other two regiments and forced them back to the west bank. Only a small number of KPA reached the east side where either they were captured, or hid until recrossing the river the following night. At dawn on August 9, 1st Cavalry Division learned of the North Korean crossing. KPA infantry had gathered on Hill 268, also known as Triangulation Hill, which was southeast of Waegwan and northwest of Taegu. The hill was important for its proximity to lines of communication, as the main Korean north–south highway and the main double-track Seoul-Pusan railroad skirted its base. 1st Cavalry Division counterattacked the KPA gathering to force them back across the river, but their initial assault was repelled. The next morning, August 10, air strikes and artillery barrages rocked Hill 268, devastating the KPA, who withdrew back behind the river.
Yongp'o The KPA plan for the attack against Taegu from the west and southwest demanded the KPA 3rd and 10th divisions make a coordinated attack. Elements of the 10th Division began crossing the Naktong early on August 12, in the vicinity of Tuksong-dong, on the Koryong-Taegu road, but were driven back. A more determined KPA crossing began early in the morning on August 14. This attack also stalled and was driven back to the river. By nightfall, the
bridgehead at Yongp'o was eliminated.
Carpet bombing In the mountains northeast of Waegwan, the ROK 1st Division continued to suffer from KPA attacks throughout mid-August. KPA pressure against the division never ceased for long. US planners believed the main KPA attack would come from the west, and so it massed its forces to the west of Taegu. It mistakenly believed up to 40,000 KPA troops were near Taegu. This number was above the actual troop numbers for the KPA, which had only 70,000 men along the entire perimeter. On August 14, General MacArthur ordered the
carpet bombing of a rectangular area on the west side of the Naktong River opposite the ROK 1st Division. On August 16, bombers dropped approximately 960 tons of bombs on the area. The attack required the entire FEAF bombing component, and comprised the largest USAF operation since the
Battle of Normandy in World War II. Information obtained later from KPA prisoners revealed the divisions the Far East Command thought to be still west of the Naktong had already crossed to the east side and were not in the bombed area. No evidence was found that the bombing killed a single North Korean soldier. However, the bombing appeared to have destroyed a significant number of KPA artillery batteries, as artillery fire on UN positions waned substantially following the mission. The UN ground and air commanders opposed future massive carpet bombing attacks unless there was precise information on an enemy concentration and the situation was critical. Instead, they recommended
fighter-bombers and
dive bombers would better support ground forces. == September push ==