JANUARIUS, a legendary Roman general. According to a story cited by R. Johanan (TJ, Av. Zar. 1:2, 39c), "The kingdoms of Egypt and Rome were at war and they proclaimed: 'How long shall we destroy one another in this war? Let us agree that the kingdom which commands its general "fall upon your sword" and he obeys – that kingdom shall rule.' The Egyptians'[general]refused, but among the Romans there was an old man by the name of Januarius [ינובריס] who had 12 sons. They said to him: 'Obey us and we will make your sons dukes, prefects, and generals.' He obeyed, and therefore they [the Romans] call it [the new year] Calendae Ianuariae [קלנדס ינובריס]. From the following day they mourn the 'black day' [מילני אימרא, μέλαιυα ὴμέρα]." The legend thus explains why the first month is called January and also gives the alleged origins of the Roman calendae, and "black day" (dies ater) on the second of January. The story has its roots in the early Roman military practice of devotio, when a general would seek to sacrifice his life on the battlefield, with the understanding that the gods are thereby obliged to preserve the army. The source before Johanan claims that Janus, the king turned deity, performed this rite of devotio; a later Christian source (De divisionibus temporum, 15) describes a similar act of sacrifice attributed to Janus, and it appears that there are a number of versions to this legend.
D. Flusser, in: Zion, 21 (1956), 100–2.