46 BCE
The last “year of confusion,” which Julius Caesar stretched to 445 days by Censorinus's count (443 by Macrobius's) so that the new calendar could begin in step with the sun in 45 BCE.
46 BCE
How the Romans fixed the year
Censorinus, On the Birthday 20–22 (238 CE), in the edition of Friedrich Hultsch (Leipzig, 1867) · 238 CE
adeo aberratum est ut G. Caesar pontifex maximus suo III et M. Aemilii Lepidi consulatu, quo retro delictum corrigeret, duos menses intercalarios dierum LXVII in mensem Novembrem et Decembrem interponeret, cum iam mense Februario dies III et XX intercalasset, faceretque eum annum dierum CCCCXLV, simul providens in futurum ne iterum erraretur: nam intercalario mense sublato annum civilem ad solis cursum formavit.
Things went so far wrong that Gaius Caesar, as chief pontiff, set out to correct the past error. In the year when he was consul for the third time, with Marcus Aemilius Lepidus, he put two extra months, of 67 days in all, between November and December. He had already inserted 23 days in February, and so he made that year 445 days long. At the same time he made sure the error would not happen again. He did away with the extra month and shaped the civil year to the course of the sun.
Where the months got their names
Macrobius, Saturnalia 1.12–14 (early fifth century CE), in the edition of Franz Eyssenhardt (Leipzig, 1893) · early fifth century CE; the dialogue is set in the 380s
ergo C. Caesar exordium nouae ordinationis initurus dies omnes, qui adhuc confusionem poterant facere, consumpsit, eaque re factum est, ut annus confusionis ultimus in quadringentos quadraginta tres dies protenderetur. post hoc imitatus Aegyptios, solos diuinarum rerum omnium conscios ad numerum solis, qui diebus tricenis sexaginta quinque et quadrante cursum conficit, annum dirigere contendit.
So when Gaius Caesar was about to start the new order, he used up all the days that could still cause confusion. As a result the last year of confusion was stretched to 443 days. After this he followed the Egyptians, the only people who understand all things divine. He set out to fit the year to the number of the sun, which completes its course in 365 and a quarter days.