“ ‘Sophie, Sophie, don’t die! Stay alive for the children,’ the dying Austrian Archduke Franz Ferdinand urged his wife as she slumped over him in the open-topped sports car. But Gavrilo Princip’s shot had already killed her. A bodyguard asked Franz Ferdinand if he was in pain. ‘It’s nothing!’ he replied repeatedly. Those were his last words.”

This is the way Simon Kuper began his Financial Times piece on what happened in Sarajevo 100 years ago on June 28, the beginning of World War I. The article is about many things, the city of Sarajevo, the doomed archduke and his morganatic bride, Sophie — virtually shunned at court on account of her low rank — but most of all Princip, the Serb nationalist, who started the conflagration with a mere pistol. There were many causes of that war — an entire bookshelf’s worth in my office alone — but the fact remains that if Princip had hesitated, if he had missed, if he had not wandered to seek a sandwich at Moritz Schiller’s delicatessen when Franz Ferdinand’s driver had taken the wrong turn, the Great War might not have happened.

And neither would have the swift collapse of four empires, the arbitrary creation of the modern Middle East, Germany’s hyperinflation, the rise of fascism, Hitler and, of course, World War II, the Holocaust, Soviet expansionism, the Cold War and so much more. The very first domino was toppled by a single man, a tubercular who was to die before the war he started had ended. The lone assassin had changed history.

He had struck before and many times since. He killed Abraham Lincoln, James Garfield and William McKinley, John F. Kennedy and his younger brother Robert, Yitzhak Rabin (and the chance for an Arab- Israeli peace), Martin Luther King Jr. and Mohandas Gandhi. One man, one weapon, and history pivoted.

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This is why the study of Vladimir Putin is so important. Russian nationalism is an indigenous force, and Russian grievance is somewhat the same. But another leader may not have fanned either one. A non-Putin, in fact, may not have felt either emotion so intensely. Dmitry Medvedev, the former Russian president and now the prime minister, probably would not have seized Crimea. Nothing about him suggests otherwise. He is no Putin.

But Putin is. The tautology has become plain. The reformer has become the uber nationalist and expansionist. He has an edge to him, a menace. He plays a losing hand, but he plays it well because while he is weak, his opponents are weaker. They vacillate. They dillydally. They fear confrontation. In fact, they abhor it. Putin knows what he wants. He will take what the West allows.

We hear now from observers of Putin, people who knew him over the years. We search for clues to his character, his tics, his weaknesses. The accounts are not encouraging. We learn he can lie. We learn he can be inscrutable. We find nothing about heavy drinking, rampant womanizing — excesses, addictions, vile bigotries. He is a good student. Strobe Talbott, a deputy secretary of state in the Clinton administration, wrote in The Post about meeting Putin in Moscow: “For no reason other than to show he had read my KGB dossier, he dropped the names of two Russian poets I had studied in college.” Impressive. I have heard similar stories about Putin. George Smiley is in the Kremlin now.

In 1943, the philosopher Sidney Hook published “The Hero in History.” Hook was a former communist moving at warp speed toward what we now would call neoconservatism. His book was a riposte to determinism; Nikita Khrushchev embodied it in 1956 when he told Western ambassadors in Moscow, “Whether you like it or not, history is on our side.” (The American version of this is “the wrong side of history” formulation — as if history has a purpose or a conscience.) Hook knew better. Men are not merely swept away by movements, they create movements. Heroes matter. Great men matter. So do evil ones.

The 20th century settled the question of whether one man can alter history. Of course he can. Hitler did. Stalin did. Churchill put steel in Britain’s backbone, and Roosevelt saved the snarling American free-enterprise system by house-breaking it. Gavrilo Princip had his moment too. On a day almost 100 years ago, he got off two shots, swiftly killing two people and, before the century had ended, probably 100 million more.

Read more from Richard Cohen’s archive.