In the ancient Roman calendar the 15th of the month was known as the Ides for a festive day dedicated to the god Mars. It was also the day on which Julius Caesar was assassinated plunging the Roman Republic into a civil war that resulted in the creation of the Roman Empire. As historic seismology is at times noting events on a calendar, it is important to note that the calendar and its days and years has evolved over time. A researcher must note the calendar system in which a historic account is recorded and reconcile it with the modern calendar to make sure the date the earthquake is accurate. If this is not done contemporary accounts that use differing calendars can seem to note different earthquakes when really they are all recording the same event. More will be said about this in later entries.