October (from Latin octo, "eight") or mensis October was the eighth of ten months on the oldest Roman calendar. It had 31 days. October followed September (from septem, "seven") and preceded November (novem, "nine"). After the calendar reform that resulted in a 12-month year, October became the tenth month, but retained its numerical name, as did the other months from September to December.
Some of the observances in October marked the close of the season for military campaigning and farming, which commenced in March (Martius, "Mars' month"). October was under the guardianship (tutela) of Mars.[1]