October (Roman month) did not number days of a month sequentially from the 1st through the last day. Instead, they counted back from the three fixed points of the month: the Nones (5th or 7th), the Ides (13th or 15th), and the Kalends (1st) of the following month. The Nones of October was the 7th, and the Ides was the 15th. The last day of October was the "pridie Kalendas Novembris," "day before the Kalends of November". Roman counting was inclusive; October 9 was "ante diem VII Idūs Octobris", "the 7th day before the Ides of October," usually abbreviated "a.d. VII Id. Oct."
Martius (month) 509 BC. Unless otherwise noted, the dating and observances on the following table are from H.H. Scullard, "Festivals and Ceremonies of the Roman Republic" (Cornell University Press, 1981), pp. 84–95. Martius (month) Martius or mensis Martius ("March") was the first month of the ancient Roman year until possibly as late as 153 BC. After that time, it was the third month, following "Februarius" (February) and preceding "Aprilis" (April). "Martius" was one of the few Roman months named for a deity, Mars, who was regarded as an ancestor of the Roman people through his sons Romulus and Remus. March marked a