At Libongao, General Suzuki prepared his defense. In the area he had his headquarters guard and a part of the 4th Airborne Raiding Regiment, in addition to a field artillery battalion, an engineering company, and a transportation company. An advance battalion of the Takahashi Detachment arrived in the sector from Palompon on the night of 17 December. General Suzuki ordered it to proceed south from Libongao and destroy the American forces in the Valencia area.[29]

As the 307th Infantry advanced north at 0900 on 19 December, it became apparent that General Suzuki had organized a defense of the highway. Many machine gun and light artillery emplacements were dug in along the road, and the enemy resistance became more determined as the troops moved north. A force estimated to be of battalion strength was dug in in depth along streams and ridges. With the use of grenades the 307th routed the defenders, the battalion from the Takahashi Detachment. The 307th Infantry pushed steadily north and at 1800 established a night perimeter; it had advanced nearly three miles and captured much enemy equipment during the day.[30]

The 306th Infantry moved out at 1100 and proceeded rapidly, without meeting resistance, to a point about 500 yards south of the Palompon road where it encountered elements of the 5th Infantry Regiment. At 1530 a battery of artillery and infantry mortars and machine guns fired upon the Japanese. In co-ordination with fire from these weapons, the 306th Infantry was then able to push forward. At 1800, though patrols from the regiment had reached the Palompon road, the regiment itself dug in for the night at a point 300 yards south of the Palompon road.[31]

On 20 December, after a five-minute artillery preparation to its front, the 307th Infantry moved out at 0830 and encountered the “strongest fortified positions” since it had left Camp Downes. The Japanese 5th Infantry Regiment and other elements of the 1st Division resisted any forward advance. By 1000 the 307th Infantry had “mowed down” and annihilated two suicide counterattacks of fifty men each on its right flank. An additional force, estimated at 2,000 men, well equipped with machine guns, mortars, and a limited amount of artillery, opposed the 307th Infantry from hastily constructed defensive positions. The attack of the enemy forces was not well co-ordinated; consequently the regiment, though slowed down, was able to continue forward. At 1549 the leading elements of the 307th Infantry were at Libongao. The enemy defensive fire increased in intensity on the northern outskirts of the village. At 1710, about 200 yards north of Libongao, the regiment repulsed a force estimated to consist of 200 Japanese armed with machine guns and mortars. The 307th Infantry established its night perimeter about 1,000 yards south of the road junction. During the day the regiment had captured many tons of ammunition and matériel in supply dumps, together with more than thirty enemy trucks. The 307th Infantry put many of the latter into serviceable condition and made immediate use of them.[32]

For the same day, 20 December, the 306th Infantry, on the left of the 307th, was assigned the mission of advancing to the Palompon road. Upon reaching the road, the 1st Battalion on the left would turn west along it to seize a bridge crossing the Togbong River and the 3d Battalion would turn east to seize the junction of the road and Highway 2.[33] During the night the enemy artillery heavily shelled the sector of the regiment. After a ten-minute artillery preparation the assault battalions moved out at 0830, and by 0925 they had reached the Palompon road. Each of the battalions thereupon started to execute its part of the mission.

The 1st Battalion pushed steadily forward and reached the eastern banks of the Togbong River at the bridge crossing, the bridge itself having been destroyed by the enemy. From a commanding ridge upon the western banks of the river, just north of the bridge site, a Japanese force estimated to be a battalion in strength opposed any further advance. The company on the left forced a passage across the river south of the bridge site, but the company on the right, despite repeated attempts, was unable to cross the river. At 1630 the 1st Battalion received orders to take up a night defensive position on the eastern banks of the river. During the night the enemy unsuccessfully launched three counterattacks against the 1st Battalion. In the morning the battalion counted more than 400 Japanese dead around its position.

The 3d Battalion, 306th Infantry, upon reaching the Palompon road turned east and encountered steadily increasing enemy opposition. By 1500, however, Company K reached the road junction. At the same time the 3d Battalion received orders to withdraw west 300 yards so that the 307th Infantry could register unrestricted fire to its front. This withdrawal was carried out and the 3d and 2d Battalions of the 306th Infantry established night positions 300 yards west of the road junction.

At 1900 General Bruce ordered the 306th Infantry to deliver harassing fire on the enemy forces to the west during the night of 20–21 December and the 307th Infantry to fire 500 yards to its front up Highway 2 and east of the highway.[34]

The Japanese 5th Infantry Regiment had assembled in the Libongao sector with orders to proceed to the Valencia sector, but the 77th Division had advanced so rapidly that it was attacking the 35th Army Headquarters. The Takahashi Detachment suffered heavy casualties and withdrew to Matagob, on the Palompon road between Palompon and Libongao. The field artillery battalion and the engineering and transportation companies that had been left at Matagob were absorbed by the Takahashi Detachment. On 21 December General Suzuki ordered the regiment to make a defensive stand, so that the main force of the 35th Army could withdraw to the Palompon sector on the shore of the Camotes Sea.[35]

During the night of 20–21 December the 77th Division artillery expended half a unit of fire, intermittently bombarding enemy positions west of the 77th Division and to the east of Highway 2. The bombardment was the most intensive made by the 77th Division during the campaign. Just before renewal of the attack on 21 December, the artillery delivered a concentrated thirty-minute preparation. General Bruce ordered the 306th Infantry to move out at 0630. Since the 1st Battalion was short of ammunition, it was to await the arrival of Company E, which had been attached to the battalion, with additional ammunition. At 1250, having received the ammunition, the battalion moved out and at 1330 secured the ridge (overlooking the bridge site), which had blocked its advance the previous day.