The Julian Calendar

When Julius Caesar defied the authority of the senate, crossed the Rubicon, and marched into Rome in 49 BC, the Roman calendar was off by 41 days. One of his first major decisions was to order a reform of the Roman calendar. With the help of Greek scholars such as Sosigenes of Alexandria, in four years, the Romans created a new calendar called the Julian calendar, which took effect from 1 January 45 BC. Several features of this calendar are in use till this day. History records 15th March 44 BC (the ides of March) as the day when Caesar was assassinated because the days were being counted through the Julian calendar. If the earlier calendar was being used, then the record keepers of that period would have recorded another date.