December 1944
| 3 | December | In Greece, fighting erupted between communists and Government forces. |
| 16 | December | The Battle of the Bulge began. |
Mediterranean
Early in the morning of 15 December, a watchful private, A.R. Rivicki of the U.S. Military Police, on guard at the No.1 Gate of Leghorn, stopped a suspicious man whose boots had given him away as a limpeteer. He turned out to be S.T.V. Francesco Pavone of the Decima Flottiglia MAS of the Italian Socialist Republic, who was to bring more limpets to the three men already landed in Leghorn in November. He did not know that all three men had been captured. Under interrogation, he revealed that he was to be joined by two other frogmen, Gino Kalbi and Giovanni Lubrano, but they were not found.
There was no special event in all theatres for Italian submarines of the Regia Marina as they continued their participation in anti-submarine exercises.