At 5 AM off Dutch Borneo, US Submarine USS S-36 is badly damaged by 7 depth charges from a Japanese destroyer while preparing to attack the destroyer.
Bataan. Japanese again attack General George Parker’s II Philippine Corps on the Abucay-Mauban line East of Mount Natib. Philippine Army 51st Division withdraws allowing Japanese to advance and occupy a hill in the Salian River valley. This and numerous other infiltrations will turn the East end of the Abucay-Mauban line by January 22nd and precipitate a withdrawal (along with other penetrations on the West side).
Malaya. By 10 AM, Japanese cross the repaired Gemencheh Bridge over the Kelamah River and engage Australian troops at Gemas. Japanese advance is held by Australian anti-tank guns, which destroy 6 tanks. In typical fashion, Japanese infantry then work around through the jungle behind the Australians who decide to withdraw across a second river (Gemas River). On the West coast at Muar, Japanese Imperial Guards (4th and 5th Regiments) overrun 4 companies from 45th Indian Brigade on the North side of Muar River (placed as forward defenses while the main bulk of 45th Brigade waits South of the river).
Operation Drumbeat. At 9.41 AM 47 miles South of East Hampton, Long Island, U-123 sinks British tanker Coimbra, carrying 9000 tons of lubricating oil which goes up in a massive explosion (36 killed, 10 survivors). Off Newfoundland, U-552 sinks Dayrose at 1.38 AM (32 crew & 6 gunners killed, 4 crew picked up by destroyers USS Ericsson and USS Stack), U-203 sinks Portuguese trawler Catalina at 11.34 AM (no survivors) and at 11.17 PM U-553 blows the bow off tanker Diala which remains afloat on her empty tanks and drifts Northeast (57 dead, 8 survivors picked up by British merchant Telefora de Larrinaga).
3900 troops of US 34th Division depart New York City for Britain on board transport ship Chateau Thierry and converted liner RMS Strathaird, escorted by 5 American destroyers (convoy AT10).
580 miles west of Gibraltar, U-93 attacks convoy HG78 on the surface. British destroyer HMS Hesperus spots U-93 on radar and rams, throwing U-93’s captain and 1st lieutenant out of the conning tower onto the HMS Hesperus's deck. U-93 is abandoned and sinks after HMS Hesperus attacks again with the deck gun and depth charges set shallow (6 dead, 40 survivors). HMS Hesperus is repaired at Gibraltar and Falmouth until April.
60 miles North of Sollum, Egypt, a British Swordfish aircraft (815 Squadron) sinks U-577 with depth charges (all 43 hands lost).