Below, the events of World War II have the "WWII" prefix.
January 1944
January 2 – WWII:
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.
Landing at Saidor: 13,000 US and Australian troops land on Papua New Guinea, in an attempt to cut off a Japanese retreat.
January 8 – WWII: 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.
The Nazi German administration expands Kraków-Płaszów concentration camp into the larger standalone Konzentrationslager Plaszow bei Krakau in occupied Poland.
January 12 – WWII: Winston Churchill and Charles de Gaulle begin a 2-day conference in Marrakech.
January 14 – WWII: Soviet troops start the offensive at Leningrad and Novgorod.
January 15
WWII: The 27th Polish Home Army Infantry Division is re-created, marking the start of Operation Tempest by the Polish Home Army, a resistance force.
1944 San Juan earthquake: An earthquake hits San Juan, Argentina, killing an estimated 10,000 people, in the worst natural disaster in Argentina's history.
January 17 – WWII:
The Battle of Monte Cassino begins in Italy. British forces cross the Garigliano River. U.S. Fifth Army troops, commanded by Lieutenant-General Mark W. Clark, arrive at the Garigliano, to begin their attack against the Gustav Line south of Rome. The French Expeditionary Corps, under command of General Alphonse Juin, moves into the mountains north of Monte Cassino.
The Soviet Union ceases production of the Mosin–Nagant 1891/30 sniper rifle.
January 20 – WWII:
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 – WWII: Operation Shingle: The Allies begin the assault on Anzio, Italy. The U.S.