Clearing the Island

Once Rock Force was ashore, operations on Corregidor evolved into a large-scale mop-up. The size of the island and the nature of the terrain precluded maneuver by units much larger than a platoon, while the generally static and disorganized defense of the Japanese led to a "campaign" of small unit assaults. Colonel Jones's plan called for the 3d Battalion, 34th Infantry, to secure Malinta Hill and contain the Japanese on the eastern end of the island while the 503d Infantry cleared Middleside and Topside. After the 503d's job had been finished, Rock Force would overrun the tail. Within this framework, operations proceeded in a series of generally uncorrelated incidents.

On the afternoon of 17 February the 1st Battalion, 503d Infantry, and other reinforcements reached Bottomside by landing craft. Japanese rifle and machine gun fire, most of which passed overhead, "expedited" the movement ashore, and the battalion soon joined the rest of the regiment on Topside. The troops already on Topside had spent the day expanding their hold, systematically reducing the first of the many Japanese bunkers, pillboxes, and underground defenses they were to encounter, and had developed a pattern for the destruction of the Japanese installations.

First, aircraft or naval fire support ships--the air arm using napalm extensively--were called upon to strike positions accessible to these types of bombardment; then the infantry attacked almost as the last shell or bomb burst. When this method failed, the 503d's own 75-mm. pack howitzers and lesser weapons were brought forward for direct fire. Next, having stationed men with submachine guns and rifles at advantageous points to cover approaches to a Japanese position, infantry assault teams moved forward behind white phosphorus hand grenades and the extremely close support of flame thrower teams. To avoid backflash and assure the deepest possible penetration of cave defenses, flame thrower operators often projected their fuel unignited, and then used white phosphorus grenades to fire it. If the Japanese within the caves still could not be induced to give up the fight, engineer demolition experts blocked the cave entrances.

One Japanese tactic was both advantageous and disadvantageous to the 503d Infantry. Each night small groups of Japanese would attempt to reoccupy positions cleared during the previous day. To the 503d, this often meant some dirty, repetitive work, and additional casualties. On the other hand, the Japanese sometimes reoccupied tactically indefensible positions that proved easy to take out. The 503d Infantry seems to have been happy to let the Japanese occasionally return to such positions, secure in the knowledge that the only result would be more Japanese killed at no cost to the attackers. The only way to keep the Japanese from reoccupying less vulnerable positions was to stop night infiltration, a process that in turn required the blocking of the underground passageways that abounded on Topside.

By these methods Japanese casualties began to mount rapidly. On the 17th, for example, over 300 Japanese were killed; nearly 775 were killed the next day. In the same two days Rock Force's casualties were approximately 30 killed and 110 wounded.

Apparently in an effort to redeem their losses in a blaze of glory, Japanese at the southern and southwestern sections of Topside attempted a counterattack in the predawn hours of 19 February. Shortly after 0200 about 40 Japanese committed suicide by blowing up an ammunition dump a few hundred yards north and inland from Breakwater Point, simultaneously killing or wounding 15-20 men of the 503d Infantry who, unaware of their danger, had been occupying a building directly over the ammunition. About the same time Japanese from Cheney Ravine and Wheeler Point, 800 yards southeast of the ravine, started a ground counterattack that reached its peak around 0600. The Japanese force, nearly 400 strong, pushed some of its troops all the way to the barracks area on Topside, but the 503d Infantry finally drove them back after 0800.¹⁵ By 1100 the 503d had hunted down the last stragglers from the counterattack and had resumed its daily process of small unit actions against known strongpoints. Operations on the 19th, including the events during the night, cost Rock Force over 30 men killed and 75 wounded, the Japanese nearly 500 killed. In addition, the 503d had captured 3 Japanese, the first prisoners of the battle.

The effort of the morning of 19 February was the last major offensive action taken by the Japanese on Topside, although small groups continued to execute un-co-ordinated banzai attacks from time to time. Some Japanese officers retained control of forces at the southwestern corner, and here resistance continued to bear some semblance of organization. The last significant opposition, centered at Wheeler Point, ended with a small-scale banzai charge on the morning of 23 February, and by 1800 that day the 503d Infantry had substantially cleared the western section of Corregidor. Colonel Jones could now direct Rock Force's full energies toward clearing the area east of Malinta Hill, which the 3d Battalion of 34th Infantry had held since the 16th.

The battalion had not been inactive at Malinta Hill. The very first night ashore it had to beat off a series of small but determined Japanese counterattacks along the north side of the hill. In these skirmishes 10 Americans were killed and a like number wounded, while about 35 Japanese lost their lives.

On the 17th the battalion devoted most of its time to securing the roads leading through Middleside so that the wounded of the 503d Infantry could be evacuated and supplies could be sent to Topside. Here, as on Malinta Hill and Topside, much of the fighting involved the laborious process of cleaning out small caves or, failing that, sealing them with explosives. At Malinta Hill every night was marked by numerous small counterattacks, executed by Japanese from Corregidor's tail or from within the hill's tunnels. Everyone feared that at any time the Japanese might set off tons of ammunition and explosives known to be stored in the tunnels, and during the night 21-22 February the expected happened. At 2130 a deafening explosion literally rocked the hill; flames shot out of tunnel entrances; rocks and other debris flew in every direction; fissures opened along the slopes; 6 men of Company A, 34th Infantry, were buried alive by a landslide on the south side.

Apparently, the Japanese had planned a controlled explosion to set the stage for a counterattack or to allow the troops inside--now estimated to number 2,000--to escape to the tail area in the ensuing confusion. If so, the explosion had gotten completely out of hand, killing an unknown number of Japanese within the tunnels. Troops of the 34th Infantry killed other Japanese who counterattacked westward, but several hundred Japanese did manage to make their way eastward under cover of the explosion and the counterattack. Additional explosions, apparently marking the suicide of Japanese still in the tunnels, shook the hill during the night of 23-24 February.

Meanwhile, Rock Force had prepared plans for the final assault against the east end of the island. The attack was to be undertaken by the 1st and 3d Battalions, 503d Infantry, while the regiment's 2d Battalion continued to mop up at Topside and the 3d Battalion, 34th Infantry, continued to hold Malinta Hill, Bottomside, and Middleside. Especially heavy air and naval bombardment preceded the attack, which began on 24 February, and the 503d's light artillery laid down the heaviest concentration of which it was capable.

The 503d's battalions first encountered serious resistance at Engineer Point, off the northeast corner of Malinta Hill, and when they overcame this they developed still stronger opposition at Infantry Point, 800 yards eastward along the north shore. Here some 600 Japanese attempted to assemble for a counterattack, but 300 of them were killed by artillery and infantry defensive fires before the attack got well under way. The remaining Japanese retreated eastward, and by nightfall on the 24th units of the 503d held all but the last 3,000 yards of the tail.