Battle of Pusan Perimeter - September Push

September Push

The North Korean Army had been pushed beyond its limits and many of the original units were at much reduced strength and effectiveness by the end of August. Logistical problems racked the North Koreans, who were devastated by shortages of food, weapons, equipment and replacement soldiers. By late August, the UN command had more combat soldiers in Korea than the North Koreans, and UN superiority over the air and sea meant the North Koreans were at a disadvantage which was growing daily. North Korean tank losses had been in the hundreds, and it had fewer than 100 tanks by 1 September, compared to the Americans' 600 tanks. By the end of August the North Koreans' only remaining advantage was their initiative. However the North Korean troops retained a high morale and enough supplies to allow for a large-scale offensive.

In planning its new offensive, the North Korean commanders decided that any attempt to flank the UN force was impossible thanks to the support of the UN navy. Instead, they opted to use frontal attacks to breach the perimeter and collapse it, as the only hope of achieving success. Fed by intelligence from the Soviet Union, the North Koreans were aware the UN forces were building up along the Pusan Perimeter and that they had to conduct an offensive soon or else forfeit the battle. A secondary objective was to surround Taegu and destroy the UN and ROK units in that city. As part of this mission, the North Korean units would first cut the supply lines to Taegu.

North Korean planners enlarged their force in anticipation of a new offensive. The army, originally numbering 10 divisions in two corps, was enlarged to 14 divisions with several independent brigades. The new troops were brought in from reserve forces based in North Korea. Marshal Choe Yong Gun served as deputy commander of the North Korean Army, with General Kim Chaek in charge of the Front Headquarters. Beneath them were the NK II Corps in the east, commanded by Lieutenant General Kim Mu Chong, and NK I Corps in the west, under Lieutenant General Kim Ung. II Corps controlled the NK 10th, 2nd, 4th, 9th, 7th, and 6th Divisions as well as the 105th Armored Division, with the NK 16th Armored Brigade and NK 104th Security Brigade in support. I Corps commanded the 3rd, 13th, 1st, 8th, 15th, 12th, and 5th Divisions with the NK 17th Armored Brigade in support. This force numbered approximately 97,850 men, although a third of it comprised raw recruits, forced conscripts from South Korea, and lacked weapons and equipment. By August 31 they were facing a UN force of 120,000 combat troops plus 60,000 support troops.

On August 20, the North Korean commands distributed operations orders to their subordinate units. These orders called for a simultaneous five-prong attack against the UN lines. This would overwhelm the UN defenders and allow the North Koreans to break through the lines in at least one place to push the UN forces back. Five battle groupings were ordered as follows:

1. NK 6th and 7th Divisions to break through the US 25th Infantry Division at Masan.
2. NK 9th, 4th, 2nd, and 10th Divisions to break through the US 2nd Infantry Division at the Naktong Bulge to Miryang and Yongsan.
3. NK 3rd, 13th, and 1st Divisions to break through the US 1st Cavalry Division and ROK 1st Division to Taegu.
4. NK 8th and 15th Divisions to break through the ROK 8th Division and ROK 6th Division to Hayang and Yongch'on.
5. NK 12th and 5th Divisions to break through the ROK Capital Division and ROK 3rd Division to P'ohang-dong and Kyongju.

On August 22, North Korean Premier Kim Il Sung ordered the war to be over by September 1, but the scale of the offensive did not allow for this. Groups 1 and 2 were to begin their attack at 23:30 on August 31, and Groups 3, 4 and 5 would begin their attacks at 18:00 on September 2. The attacks were to closely connect in order to overwhelm UN troops at each point simultaneously, forcing breakthroughs in multiple places that the UN would be unable to reinforce. The North Koreans also relied primarily on night attacks to counter the UN's major advantages in air superiority and naval firepower. North Korean generals thought such night attacks would prevent UN forces from firing effectively and result in large numbers of UN friendly fire casualties.

The attacks caught UN planners and troops by surprise. By August 26, the UN troops believed they had destroyed the last serious threats to the perimeter, and anticipated the war ending by late November. ROK units, in the meantime, suffered from low morale thanks to their failures to defend effectively thus far in the conflict. A cautious Lieutenant General Walker ordered Major General John B. Coulter to the P'ohang-dong area to shore up the ROK I Corps, which was falling apart thanks to their low morale. UN troops were preparing for Operation Chromite, an amphibious assault on the port of Inchon on September 15 and did not anticipate the North Koreans would mount a serious offensive before then.

The Great Naktong Offensive was one of the most brutal fights of the Korean War. The North Koreans were initially successful in breaking through UN lines in multiple places and made substantial gains in surrounding and pushing back UN units. On September 4–5 the situation was so dire for the UN troops that the US Eighth Army and ROK Army moved their headquarters elements from Taegu to Pusan to prevent them from being overrun and losing their heavy communications equipment, though Walker remained in Taegu with a small forward detachment. They also prepared their logistics systems for a retreat to a smaller defensive perimeter called the "Davidson Line." By September 6, however, Walker decided another retreat would not be necessary.

The five-prong offensive led to heavy fighting around Haman, Kyongju, Naktong Bulge, Nam River, Yongsan, Tabu-Dong and Ka-san. The North Korean attacks made appreciable gains and forced the UN troops along the Pusan Perimeter to form a thin line of defense, relying on mobile reserves for the strength to push back North Korean attackers. From September 1 – 8 this fighting was intense and the battle was a very costly deadlock for the two overextended armies. By September 15, though, North Korean troops were caught unaware by Operation Chromite, and those forces that remained intact after 15 days of fighting were forced to retreat in a total rout. Isolated North Korean resistance continued until September 18, but on that date UN troops were mounting a full-scale breakout offensive and pursuing retreating North Korean units to the north, ending the fighting around the Pusan Perimeter.