Why do we still care about Julius Caesar, more than 2,050 years after his death? History may be the least of it. For modern readers, Caesar was immortalized by William Shakespeare. His 1599 drama The Tragedy of Julius Caesar offers a Renaissance-era Christian spin on a pagan story: we behold Caesar’s moment of supreme power, his assassination by Rome’s self-proclaimed liberators, and their disastrous end. No small part of the story, at least in Shakespeare, is the personal betrayal of Caesar by his friend, Marcus Junius Brutus. Upon seeing the dagger in Brutus’ hand, Caesar cries out at the sign of treachery: “Et tu, Brute?”

For Americans, Shakespeare’s Caesar, a would-be tyrant killed in the name of liberty, is a foundational symbol. From George III on, every powerful American leader, including many if not most American presidents, has been accused of being a new Caesar. In the wider world, a variety of emperors have called themselves “Caesar,” from the Romans to the Russians—whose word “tsar” comes from Caesar—and the Germans, whose “kaiser” also comes from Caesar. Then there is Caesarism, or rule by strongman, a phenomenon associated with politicians beginning with Napoleon Bonaparte and ranging from Benito Mussolini to Vladimir Putin.

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But there’s more: we are told that Caesar was also a rake, though he denied the accusation of having had an affair with an elderly Greek king as a young man on the make. In any case, he is better known for his operatic connections with a variety of women. In addition to his three (or possibly four) wives, Caesar had a torrid love affair with Servilia, the half-sister of his arch-rival, the conservative senator Marcus Cato “the Younger,” and the mother of his future assassin, Brutus. He slept with one Eunoë, wife of the king of Mauretania (Morocco), a political ally. But Caesar’s best-known liaison was with Egypt’s Cleopatra VII Philopator. The queen claimed that their affair produced a son, Ptolemy XV Caesar, better known by the nickname “Caesarion.” Caesar never affirmed his paternity, but he allowed Cleopatra to name the boy after him. The affair is the subject of an opera by George Frideric Handel and a play by George Bernard Shaw. So whether in politics, war, literature, or romance, Caesar casts a wide cultural shadow.

But Gaius Julius Caesar was also a real historical figure—a Roman statesman, general, and writer born on July 13, 100 B.C. and assassinated on March 15, 44 B.C. At the time of his death at the age of 55, he was the most powerful man in the Roman Empire and possibly the world. Scion of an old but now second-tier patrician family, he rose to the highest office in the state due to his extraordinary political skills. He was a brilliant writer; his war commentaries, The Gallic War and The Civil War, are classics. And he was equally talented as a general. He conquered Gaul (roughly France and Belgium), invaded Germany and England, and defeated the forces of the Roman state in a civil war whose battles were fought from one end of the Mediterranean to the other. His power secured by force of arms, Caesar became the first man in Roman history to be named dictator for life. In the spring of 44 he was about to depart Rome to avenge past defeat and shore up the eastern border against a resurgent rival empire, the Parthians. He never left the city, however. His enemies suspected him of wanting to become king. And so 60 senators conspired to assassinate him at a meeting of the Senate, Rome’s highest and most prestigious political body, on a minor spring holiday known as the Ides of March. Rather than hiring a hit man, the conspirators actually wielded the daggers that killed Caesar: it was personal. The best-known conspirator, Brutus, was no friend of Caesar’s. It seems he was untroubled by any sense of personal betrayal. Nor did Caesar ever say “Et tu, Brute?” There was a rumor that he said, in Greek, “You too, child?” but the best sources wisely dismiss the tale.

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Caesar’s assassination did not restore the liberty of the republic. Instead, it brought Rome approximately another 15 years of civil war. When peace was finally restored, Rome was still a republic in name but in fact it had become a monarchy. The de facto king—officially, just the “first citizen”—was Caesar’s great-nephew, the former Gaius Octavius, whom Caesar had taken under his wing and then named in his will as primary heir and posthumous adoptee. The young man fought his way to supreme power after Caesar’s death and was rewarded with the title of “Revered One,” that is, Augustus. From his reign onward, every Roman emperor took the title of Caesar.

Julius Caesar is utterly fascinating, but he leaves the historian with more questions than answers. The evidence for his life is relatively rich by the slim standards of ancient history, but it is deeply partisan and highly colored by later events. So it is not surprising that there are as many interpretations of Caesar as there are historians. For some, he was indeed a tyrant, the man who would be king. For others, he was a true friend of the Roman people, even a democrat. For some, Caesar rescued Rome from a purblind oligarchy; for others, he selfishly destroyed the republic and its freedom. For some, the end of the republic was inevitable and even welcome. For others, it was an accident that could and should have been avoided.

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Into this debate comes an important contribution by Robert Morstein-Marx, a professor of classics at the University of California, Santa Barbara. Morstein-Marx has published many distinguished books, offering particular insight into the study of oratory and politics in the late Roman Republic. In Julius Caesar and the Roman People, he takes up one of the historical profession’s great themes: what brought down the Roman Republic? Or, rather, who? Who bears more responsibility, Caesar or his political enemies? The book is lengthy (over 600 pages) and detailed. Its impressive erudition is displayed in over 2,000 footnotes and more than 25 pages of bibliography.

Morstein-Marx largely absolves Caesar of blame. Caesar, he argues, was an ambitious and immensely successful Roman statesman and general in the mold of the great men of the republic’s past. He had no interest in becoming a tyrant, much less a king. The real problem was his opponents, who overreacted to his success and brought on violence. Cato was a hero to 18th-century lovers of liberty on both sides of the Atlantic, from the playwright and essayist Joseph Addison to George Washington. But in Morstein-Marx’s view, he was the villain of the age. Compromise was possible, but Cato was intractable, and the result was civil war.

So according to Morstein-Marx, what really brought down the republic was a combination of repeated and savage blows: the civil war of 49-45, followed by the Ides of March, and in turn by the renewed civil wars that only ended after the battle of Actium in 31. Arguing in the vein of his mentor, the great U.C. Berkeley classicist Erich Gruen, Morstein-Marx maintains that the republic was not doomed to fail. On the contrary, it was healthy and vibrant. What brought it down was not some vast historical force. Rather, it was the actions of individuals—mistaken, ignorant, foolish, or egotistical—that destroyed the system over time.

Historians famously come in two forms: lumpers, who look for truth in the big picture, and splitters, who seek truth in the details. Morstein-Marx is a splitter, and an excellent one. His command of the details is marvelous. The book offers many powerful reinterpretations of oft-told tales, such as Caesar’s march across the river that served as a boundary between Rome and its northern territories, the Rubicon. Morstein-Marx writes:

[I]t was not Caesar’s crossing of the Rubicon but the Senate’s Final Decree of January 7, 49, that precipitated the military phase of the crisis. Even so, despite this virtual declaration of war, and despite Caesar’s swift reaction of crossing the Rubicon into Italy with one legion,…until Pompey’s departure from Brundisium in mid-March it remained uncertain to contemporaries whether there truly was a war on or whether the military movements that ensued in Italy were the prelude to the conclusion of a settlement between the two former allies and adfines, now adversaries.

As Morstein-Marx argues, hindsight is one of the historian’s greatest enemies. Many things that look inevitable in retrospect surely weren’t. A violent separation between the Thirteen Colonies and Great Britain, the fall of France in 1940, the triumph of Communism in China: none of these events was written in the stars. All could have been avoided.

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History is full of accidents and contingencies. And yet, history is also marked by tendencies. Democracies tend to breed demagogues, who can pose a serious and even fatal threat in times of crisis: see Athens during the Peloponnesian War. Militaristic regimes face the “occupational hazard” of substituting tactics and operations for strategy, and the result can be losing a war: for example, Germany in both world wars. From Cleopatra to Catherine the Great to today’s politicians, powerful women tend to generate bigoted criticism from men (and even from some women) who feel threatened by strong females.

Morstein-Marx has done a great service to the historical profession by making the case for skepticism about Caesar’s alleged monarchical ambitions. He does so with all the incisiveness and rigor of a historian at the height of his powers. His work will make all scholars rethink and sharpen their arguments. As Morstein-Marx demonstrates, the evidence that Caesar long hungered after dictatorial power, let alone that he brought down the republic, is hardly clear-cut.

Nor was Rome fated to pass from republic to monarchy. So Morstein-Marx shows, but one might take the argument in a different direction. For the republic to survive, Rome needed to undergo massive political changes. The cliché remains true: the institutions that governed a city-state were not suited to govern an empire. The Roman Empire could have continued to be run by a Senate encompassing the super-rich and enormously powerful, with an almost equally rich and potent class of equestrians beneath them. Instead of an emperor, it could have been run by an executive committee. Rome could not, however, have remained in the hands of a narrow oligarchy hailing largely from in and around the city of Rome. Both the Senate and the equestrian order would need to expand to include more Italians and more provincials. What brought down the republic was the inability of its elite to adjust to the overwhelming set of problems brought about by its very success. The world had changed because Roman soldiers and statesmen had changed it. Like Pompey the Great before him, Caesar understood. Others, like Cato and Marcus Cicero, insisted on the old ways—to the point of dying with them.

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But what of Caesar’s ambitions? Maybe he didn’t have autocratic goals, but was he simply a ruthless go-getter determined to win every battle at any cost? As Morstein-Marx argues, Rome wasn’t an oligarchy but a republic. The people counted for something, and the people favored Caesar. When Caesar told his troops in 49 B.C. that he was going to war not just to defend his own rank and status, but to defend the office of the people’s tribunes and the popular liberty they represented, he meant to be taken seriously.

War, as Morstein-Marx argues, is an accelerant. It makes change seem inevitable when it had previously appeared inconceivable. No civil war, no Caesar? If peace had prevailed in 49, perhaps the conqueror of Gaul would have been content to come home and dominate Roman politics, as Pompey had done before him after conquering the East. To be sure, by 49 B.C. Caesar had already seen war and enjoyed kinglike power while in Gaul. From 58 to 50 he had raised his own army, amassed a fortune, and attracted a long list of clients—precisely the things that worried his opponents in Rome. And most people aren’t saints. They aren’t even lawyers, like Cicero or Abraham Lincoln. They would rather light fires than find middle ground. Cato and his followers might have chosen compromise in 49 B.C., just as the South might have chosen compromise in 1861 and accepted the inauguration of Abraham Lincoln. American slavery then might have continued for a long time, God forbid. But proud people don’t compromise, and Cato and Caesar were both very proud. So were many others in Rome.

Besides, what starts as incremental change sometimes leads to radical developments. If, to take the American case, a Republican-led government in 1861 had abolished slavery in the territories, pressure would have mounted to abolish slavery in the Southern states as well, and it might have proved irresistible. If Caesar had returned to Rome in peace in 49 B.C. and won a second term as consul, would he have been content to stay there afterward? Surely he would have wanted another extraordinary command, this time in the East, to conquer Dacia and make war on Parthia as he would indeed set out to do in 44 B.C. There he would have faced the temptation of more wealth, more power, more adulation—even, perhaps, the chance to father a pharaoh by Cleopatra. More war, more accelerant. And would an even more powerful Caesar have found that you can’t go home again, if home meant being just a member of the crew? In this alternate universe, would he have decided to do much of what he did after the civil war?

The historical Caesar suspended normal elections, accepted honors up to and including divinization, had a new forum built and dedicated to himself and his family, had the original Rostra (Speaker’s Platform) rebuilt with two statues of himself, and, above all, became “Dictator in Perpetuo”—a title that Morstein-Marx translates as “Continuous Dictator” but which, he agrees, was reasonably translated into Greek as “Dictator for Life.” These were not the actions of a Roman politician with respect for the republic and its norms.

Then there was Cleopatra. At the time of Caesar’s assassination, she had spent the better part of the past two years not in Egypt but in Rome, living across the Tiber not in some hotel but in Caesar’s villa. She arguably was accompanied by her son and her younger brother, Ptolemy XIV, in theory her co-ruler but in practice her subordinate. There is reason to think she was pregnant again by Caesar, only to suffer a miscarriage. Ordinary Roman politicians didn’t stash their mistresses, who happened to rule the richest kingdom in the Mediterranean, in Rome’s suburbs. Morstein-Marx compares Caesar to another titan among Rome’s generals, Scipio Africanus, defeater of the Carthaginian invader Hannibal and one of antiquity’s greatest commanders. A faction in the Senate turned on Scipio, as it later would turn on Caesar, and drove him from power. But Scipio did not respond by starting a civil war, nor did he rule a province like a king or take a wealthy foreign queen as mistress.

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Caesar’s assassins, as Morstein-Marx rightly argues, were not necessarily idealists. Some were moved by no higher motive than self-interest, as they could see no future for their careers under Caesar. But they were right to think that Caesar intended to dominate the polity in a way that precluded the ordinary give-and-take of republican politics. Assassination was the wrong move, though, especially because the assassins were incompetent when it came to carrying through on the coup.

By March of 44 B.C. Caesar was, as Shakespeare wrote, a colossus. He hadn’t outgrown the Senate; he had outgrown Rome. That’s what makes him a world-historical figure. His opponents played on a narrower stage. Had they acted differently, they could have stopped Caesar, as Morstein-Marx explains so well. But they couldn’t have stopped the changes that were already sweeping over the republic.