January 2: Free French General Jean de Lattre de Tassigny is appointed to command French Army B, part of the Sixth United States Army Group in North Africa.
January 4: The Battle of Monte Cassino begins in Italy.
January 5: The Daily Mail becomes the first transoceanic newspaper.[vague]
January 8: Philippine Commonwealth troops enter the province of Ilocos Sur in northern Luzon and attack Japanese forces.
January 11: President of the United States Franklin D. Roosevelt proposes a Second Bill of Rights for social and economic security in his State of the Union address. - Kraków-P?aszów concentration camp established.
January 12: Winston Churchill and Charles De Gaulle begin a 2-day wartime conference in Marrakech.
January 14: Soviet troops start the offensive at Leningrad and Novgorod.
January 15: The 27th Polish Home Army Infantry Division is re-created, marking the start of Operation Tempest by the Polish Home Army. - An earthquake hits San Juan, Argentina, killing an estimated 10,000 people in the worst natural disaster in the country's history.
January 17: British forces in Italy cross the Garigliano River. - Meat rationing ends in Australia. - The Soviet Union ceases production of the Mosin-Nagant 1891/30 sniper rifle.
January 20: The Royal Air Force drops 2,300 tons of bombs on Berlin. - The United States 36th Infantry Division, in Italy, attempts to cross the Rapido River.
January 22: Operation Shingle: The Allies begin the assault on Anzio, Italy. The U.S. 45th Infantry Division stands their ground at Anzio against violent assaults for 4 months.
January 27: The 2-year Siege of Leningrad is lifted.
January 29: The Battle of Cisterna takes place.
January 29: HMS Spartan (95) is sunk by a Henschel Hs 293 guided missile from a German aircraft off Anzio, western Italy.
January 30: United States troops invade Majuro, Marshall Islands.
January 31: Battle of Kwajalein: American forces land on Kwajalein Atoll and other islands in the Japanese-held Marshall Islands. (source: Wikipedia)