Consisting of the 5th, 16th, and 18th Infantry Regiments and strongly supported by artillery and armor, the 4th Division was among the most distinguished of the major Communist units. With the 107th Tank Regiment attached at the outset of the invasion, it had breezed through Uijongbu before sharing in the capture of Seoul. On 5 July 1950, the 4th became the first NKPA outfit to tangle with the newly arrived United States Army forces. Task Force Smith delayed it a few hours near Osan, despite the Reds’ great advantage in numbers and armor. Later, after capturing Nonsan and aiding in the reduction of Taejon, the unit was selected to spearhead the assault over the Naktong. _Task Force Hill Organized_ In an effort to plug the hole in the Pusan Perimeter, General Walker attached the 9th Infantry (2d Infantry Division) commanded by Colonel John G. Hill, to the 24th Division. In turn, General Church placed Colonel Hill in control of all units in his southern zone and ordered a counterstroke against the Naktong Bulge. Task Force Hill attacked on 11 August but lost its momentum in a confused situation which found the enemy attacking at the same time. Reinforced to a strength of three infantry regiments, Hill’s provisional unit again struck out against the bridgehead on 14 and 15 August. After encountering a stone wall of resistance, the task force was ordered to cease the attack and defend the ground it occupied east of the enemy pocket.[275] [275] _Ibid._ This was the situation as outlined to General Craig at the planning conference, and he was also briefed on the topography of the target area. The Naktong Bulge west of Yongsan results from a bend in the river resembling a stubby thumb pointing westward. Bounded on three sides by the stream, with its inland border formed by a long valley, the bulge is an isolated terrain feature--a fortress of mountains topped by Hill 311, the key height. As the Yongsan road reaches the Bulge from the east, it turns southwest, winds around Hill 311, and stops at the tip of the “thumb” where a ferry links it to the road west of the river. Guarding the eastern approach to the natural fortress are two hills astride the Yongsan road--Finger Ridge to the north and Hill 207 to the south. The former is set off on the east by a deep gully containing the village of Tugok. Eastward from Hill 207 and directly below Tugok is Obong-ni Ridge--so called because of a village by that name at its eastern base. Not only had the NKPA 4th Division overrun the Naktong Bulge; it had pushed on along the road to Yongsan, seizing Hill 207, Tugok, and both Finger and Obong-ni Ridges. These latest gains and the Bulge itself were being consolidated by elements of all three regiments.