depriving the priests of some of their power but allowing for a more consistent calendar for official business. Julian reform Julius Caesar, following his victory in his civil war and in his role as pontifex maximus, ordered a reformation of the calendar in 46BC. This was undertaken by a group of scholars apparently including the Alexandrian Sosigenes and the Roman M. Flavius. Its main lines involved the insertion of ten additional days throughout the calendar and regular intercalation of a single leap day every fourth year to bring the Roman calendar into close agreement with the solar year. The year 46BC was the last of the old system and included three intercalary months, the first inserted in February and two more— and —before the kalends of December. Later reforms After Caesar's assassination, Mark Antony had Caesar's birth month Quintilis renamed July () in his honor. After Antony's defeat at Actium, Augustus assumed control of Rome and, finding the priests had (owing to their inclusive counting) been intercalating every third year instead of every fourth, suspended the addition of leap days to the calendar for one or two decades until its proper position had been restored. See Julian calendar: Leap year error. In 8BC, the plebiscite Lex Pacuvia de Mense Augusto renamed Sextilis August () in his honor. In large part, this calendar continued unchanged under the Roman Empire. (Egyptians used the related Alexandrian calendar, which Augustus had adapted from their wandering ancient calendar to maintain its alignment with Rome's.) A few emperors altered the names of the months after themselves or their family, but such changes were abandoned by their successors. Diocletian began the 15-year indiction cycles beginning from the AD297 census; these became the required format for official dating under Justinian. Constantine formally established the 7-day week by making Sunday an official holiday in 321. Consular dating became obsolete following the abandonment of appointing nonimperial consuls in AD541. The Roman method of numbering the days of the month never became widespread in the Hellenized eastern provinces and was eventually abandoned by the Byzantine Empire in its calendar. Days Roman dates were counted inclusively forward to the next one of three principal days within each month: Kalends ( or ), the 1st day of each month Nones ( or ), the 7thday of "full months" and 5thday of hollow ones, 8days—"nine" by Roman reckoning—before the Ides in every month Ides