Russians recapture Liudinovo, southwest of Kaluga, Tikhonovo Pustyn railway junction, northwest of Kaluga and Popovka in Donets Basin (Ukraine). Number of coal mines in the Donets are back in production.
Battle of Mozhaisk: Russians oust Germans from stronghold west of Moscow (ends January 19).
Atlantic – Operation Paukenschlag (‘Drumbeat’): 5 U-boats commence operations off American East Coast – 20 ships sunk January 11 to February 7.
Pacific: US carrier Saratoga damaged by Japanese submarine I-6 off Hawaii.