Re: While you're there ...
The Julian calendar reform didn't add any months; there were already 12 by the time that Julius Caesar changed the calendar. Arguably they removed one, since an intercalary month was removed. The reason for the numbering of the second half of Roman month names being apparently regular but out of whack (Quintilis, Sextilis, Sept through to Dec- ember) isn't really known. Later Romans believed there were originally only ten, their supposed "calendar of Romulus" lacks January and February, but modern historians doubt it, there may never have been ten. For a while those two months were at the end of the year and probably moved to the start about 100 years before Julius.
By the time of the Julian reform the Roman calendar was mad. Between 355 and 378 days in a year, depending on the decrees of the pontifices (there's a reason the term sounds familiar), a decision theoretically made to keep the seasons in line, but usually practically made to influence political terms of office. Is it the nones, the ides or the kalends of the month?
https://en.wikipedia.org/wiki/Julian_calendar is a fascinating insight into classical era astronomy, politics and international relations with a bit of date accounting tossed in on top. But anyone who thinks DD/MM/YYYY versus MM/DD/YYYY is an eldritch horror had better not read it.
Biting the hand that feeds IT
