Julius Caesar's bloody assassination on March 15, 44 B.C., forever marked March 15, or the Ides of March, as a day of infamy. It has fascinated scholars and writers ever since.

For ancient Romans living before that event, however, an ides was merely one of several common calendar terms (see sidebar) used to mark monthly lunar events. The ides simply marked the appearance of the full moon.

But the Ides of March assumed a whole new identity after the events of 44 B.C. The phrase came to represent a specific day of abrupt change that set off a ripple of repercussions throughout Roman society and beyond.

Josiah Osgood, an assistant professor of classics at Georgetown University in Washington, D.C., said: "You can read in Cicero's letters from the months after the Ides of March. … He even says, 'The Ides changed everything.'"

By the time of Caesar, Rome had a long-established republican government headed by two consuls with joint powers. Praetors were one step below consuls in the power chain and handled judicial matters. A body of citizens forming the Senate proposed legislation, which general people's assemblies then approved by vote. A special temporary office, that of dictator, was established for use only during times of extreme civil unrest.

The Romans had no love for kings. According to legend, they expelled their last one in 509 B.C. While Caesar had made pointed and public displays of turning down offers of kingship, he showed no reluctance to accept the office of "dictator for life" in February 44 B.C. According to Osgood, this action may have sealed his fate in the minds of his enemies. "We can see [now] that that was enough to get him killed," Osgood said.

Caesar had pushed the envelope for some time before his death. "Caesar was the first living Roman ever to appear on the coinage," Osgood said. Normally, the honor was reserved for deities. He notes that some historians suspect that Caesar might have been attempting to establish a cult in his honor in a move towards deification.

It is unclear if Caesar was aware of the plot to kill him on March 15 in 44 B.C. But Caesar was not oblivious to the mounting danger of a backlash, noted Charles McNelis, an assistant professor of classics and Osgood's colleague at Georgetown University.

The plot's conspirators, who termed themselves "the liberators," had to move quickly. "Caesar had plans to leave Rome on March 18th for a military campaign in Parthia, the region around modern-day Iraq. So the conspirators did not have much time," McNelis said. Whether or not Caesar was a true tyrant is debated still to this day. It is safe to say, however, that in the mind of Marcus Brutus, who helped mastermind the attack, the threat Caesar posed to the republican system was clear.

Brutus's involvement in the murder is made tragic given his close affiliations with Caesar. His mother, Servilia, was one of Caesar's lovers. And although Brutus had fought against Caesar during Rome's recent civil war, he was spared from death and later promoted by Caesar to the office of praetor.

"Caesar had always … tried to cultivate talent that he saw in younger people," Osgood said. "And Brutus was no exception."

Brutus, however, was torn in his allegiance to Caesar, Osgood noted. Brutus's family had a tradition of rejecting authoritarian powers. Ancestor Junius Brutus was credited with throwing out the last king of Rome, Tarquin Superbus, in 509 B.C. Ahala, An ancestor of Marcus Brutus's mother, had killed another tyrant, Spurius Maelius. This lineage, coupled with a strong interest in the Greek idea of tyranicide, disposed Brutus to have little patience with perceived power grabbers.

The final blow came when his uncle Cato, a father figure to Brutus, killed himself after losing in a battle against Caesar in 46 B.C. Brutus may have felt shame over accepting Caesar's clemency and obligation to do Cato honor by continuing his quest to "save" the republic from Caesar, Osgood speculated.

It is this moral dilemma that has caused debate over whether or not Brutus should be branded a villain. Plutarch's Life of Brutus, Osgood noted, is quite sympathetic in comparison to surviving documents naming other enemies of Caesar and his successors.

Shakespeare later used Plutarch's Brutus as one of the bases for his play Julius Caesar, where Brutus is portrayed as a tragic hero and Caesar as an unequivocal tyrant. The poet Dante, however, took a different stance: Brutus, in killing the man who spared him, was doomed to the lowest levels of hell. "He's perceived not as a liberator but [as] somebody who threatened the stability of the political system," McNelis said.

Scholars disagree on just who was the on the side of "good." McNelis believes neither side is entirely in the clear. "We need to realize that we're dealing with very brutal and ruthless men on both sides."

In the end, the legacy of power Caesar established lived on through his heir Octavian, who later became Rome's first emperor, also known as Imperator Caesar Augustus. The Ides of March remained a pithy reminder to future rulers, according to McNelis. "Octavian seems to have been aware of the problems of presenting himself as Caesar had. … The Ides became a lesson in political self-presentation," he said.