Wiki sourced:

From 7 to 14 January 1942, the Japanese concentrated on reconnaissance and preparations for an attack on the Main Battle Line from Abucay to Mount Natib to Mauban. At the same time, in a critical mistake, they also relieved the 48th Division, responsible for much of the success of Japanese operations, with the much less-capable 65th Brigade, intended as a garrison force. The Japanese 5th Air group was withdrawn from operations on 5 January in preparation for movement with the 48th Division to the Netherlands East Indies. U.S. and Filipino forces repelled night attacks near Abucay, and elements of the U.S. Philippine Division counterattacked on 16 January. This failed, and the division withdrew to the Reserve Battle Line from Casa Pilar to Bagac in the center of the peninsula on 26 January.

The 14th Army renewed its attacks on 23 January with an attempted amphibious landing behind the lines by a battalion of the 16th Division, then with general attacks beginning 27 January along the battle line. The amphibious landing was disrupted by a PT boat and contained in brutally dense jungle by ad hoc units made up of U.S. Army Air Corps troops, naval personnel, and Philippine Constabulary. The pocket was then slowly forced back to the cliffs, with high casualties on both sides. Landings to reinforce the surviving pocket on 26 January and 2 February were severely disrupted by air attacks from the few remaining FEAF P-40s, then trapped and eventually annihilated on 13 February.

A penetration in the I Corps line was stopped and broken up into several pockets. General Homma on 8 February ordered the suspension of offensive operations in order to reorganize his forces. This could not be carried out immediately, because the 16th Division remained engaged trying to extricate a pocketed battalion of its 20th Infantry. With further losses, the remnants of the battalion, 378 officers and men, were extricated on 15 February. On 22 February, the 14th Army line withdrew a few miles to the north and USAFFE forces re-occupied the abandoned positions. The result of the “Battle of the Points” and “Battle of the Pockets” was total destruction of all three battalions of the Japanese 20th Infantry and a clear USAFFE victory.

For several weeks, the Japanese, deterred by heavy losses and reduced to a single brigade, conducted siege operations while waiting refitting and reinforcement. Both armies engaged in patrols and limited local attacks. Because of the worsening Allied position in the Asia-Pacific region, U.S. President Franklin D. Roosevelt ordered MacArthur to relocate to Australia, as Supreme Allied Commander South West Pacific Area. (MacArthur’s famous speech regarding the Philippines, in which he said “I came out of Bataan and I shall return” was made at Terowie, South Australia on 20 March.) Wainwright officially assumed control of what was now termed United States Forces in the Philippines (USFIP) on 23 March. During this period, elements of the U.S. Philippine Division were shifted to assist in the defense of other sectors.

Beginning 28 March, a new wave of Japanese air and artillery attacks hit Allied forces who were severely weakened by malnutrition, sickness and prolonged fighting. On 3 April, the Japanese began to break through along Mount Samat, estimating that the offensive would require a month to end the campaign. The U.S. Philippine Division, no longer operating as a coordinated unit and exhausted by five days of nearly continuous combat, was unable to counterattack effectively against heavy Japanese assaults. On 8 April, the U.S. 57th Infantry Regiment (PS) and the 31st Division PA were overrun near the Alangan River. The U.S. 45th Infantry Regiment (PS), under orders to reach Mariveles and evacuate to Corregidor, finally surrendered on 10 April 1942. Only 300 men of the U.S. 31st Infantry successfully reached Corregidor.