Editing Julian calendar (section)

=== Months ===

The Julian months were formed by adding ten days to a regular pre-Julian Roman year of 355 days, creating a regular Julian year of 365 days. Two extra days were added to January, Sextilis (August) and December, and one extra day was added to April, June, September, and November. February was not changed in ordinary years, and so continued to be the traditional 28 days. Thus, the ordinary (i.e., non-leap year) lengths of all of the months were set by the Julian calendar to the same values they still hold today.

The Julian reform did not change [[Roman calendar#Months|the method used to account days of the month in the pre-Julian calendar]], based on the Kalends, Nones and Ides, nor did it change the positions of these three dates within the months. Macrobius states that the extra days were added immediately before the last day of each month to avoid disturbing the position of the established religious ceremonies relative to the Nones and Ides of the month.<ref>Macrobius, [https://penelope.uchicago.edu/Thayer/L/Roman/Texts/Macrobius/Saturnalia/1*.html#14.9 ''Saturnalia'' 1.14.9] (Latin). Exceptionally, the extra day in April was inserted as the 26th, a.d. VI Kal. Mai. in the Julian calendar, in order to avoid adding a day to the [[Floralia]], which ran from a.d. IV Kal. Mai. (27 April in the pre-Julian calendar) to a.d. V Non. Mai.</ref>

The inserted days were all initially characterised as ''dies fasti'' ('''F''' – see [[Roman calendar#Character of the day|Roman calendar]]).<ref>Macrobius, [https://penelope.uchicago.edu/Thayer/L/Roman/Texts/Macrobius/Saturnalia/1*.html#14.12 ''Saturnalia'' 1.14.12] (Latin).</ref> The character of a few festival days was changed. In the early Julio-Claudian period a large number of festivals were decreed to celebrate events of dynastic importance, which caused the character of the associated dates to be changed to '''NP'''. However, this practice was discontinued around the reign of [[Claudius]], and the practice of characterising days fell into disuse around the end of the first century AD: the Antonine jurist [[Gaius (jurist)|Gaius]] speaks of ''dies nefasti'' as a thing of the past.<ref>A. K. Michels, ''The Calendar of the Roman Republic'' Appendix II; J. Rüpke, ''The Roman Calendar from Numa to Constantine'' 113–114, 126–132, 147.</ref>