Fifth Phase Offensive: First Impulse: (Map 10) Late friendly reports of 22 Apr[il] 51, indicated that the enemy had apparently opened the long anticipated "Fifth Phase Offensive", which had been variously reported as scheduled to begin generally between 15-30 April. Fragmentary reports indicated that the centre of attack was in the Wacho-Panam area. The appearance of elements of the 20th CCF [Chinese Communist Field] Army in the Kumhwa area and accelerated enemy activity, including a southward movement of troops in the Chorwon area constituted the most significant developments along the 1st US Corps front on 22 April. Minor probing attacks and the utilisation of artillery fire against friendly central and right flank units also characterised enemy activity during the period.
On 23 April, following an intense artillery preparation, the enemy launched a general attack along the UN [United Nations] front from Changdan east to Nodong and succeeded in penetrating friendly positions at widely scattered points. To contain these penetrations and solidify the front, Eighth Army initiated a planned displacement to the rear.
Strongest hostile attacks were hurled against the 24th US Division in the Sinsul area, at the 6th ROK [Republic of Korea] Division in the Sillae area, and at the 5th ROK Division in the Sinchon area.
Although the enemy had committed himself to the conduct of strong offensive operations in the area of the 24th US and 6th ROK Divisions, as of 24 April, it was still too early to determine the full meaning of his operations. While these relatively strong counterattacks were considered to be the forerunner of more powerful counterthrusts against UN forces, the effort was immediately significant as a definite indication that the enemy intended to stiffly contest any further UN advances into North Korea. For the previous three months, UN forces had been pushing steadily forward against strong enemy delaying actions, while fresh units from Manchuria were concentrated in forward areas and battle-worn CCF and NK [North Korean] units were being rehabilitated.
The enemy, by concentrating six rehabilitated divisions of the 20th and 27th CCF Armies in the former zone of the 40th CCF Army, had definitely provided the necessary force to exploit any success in the sector. In addition to this provision for a powerful penetrating effort, huge enemy forces were