The Ides of March fall on the fifteenth day of March in the Roman Calender. The date became significant when Julius Caesar was assassinated in 44 B.C. After his assassination, the Ides of March became synonymous with doom and hardship.BBC: Ides of March
Why Was Caesar Assassinated?
For more than fifty years before Caesar's assassination, Rome had been anti-royalty, and though Caesar had made many public displays of refusal of the crown, he had acted the role of dictator and was in the process of claiming the position of "Dictator for Life." Caesar became the first ruler to appear on coinage (a position that had always been given to the gods,) and rumors told that he was even putting together a cult of people who would eventually raise him up to God status.National Geographic: Ides of March Marked Murder of Julius Caesar
