In these pages nearly seven years ago, Timothy Snyder asked the provocative question: Who killed more, Hitler or Stalin? As useful as that exercise in moral rigor was, some think the question itself might have been slightly off. Instead, it should have included a third tyrant of the twentieth century, Chairman Mao. And not just that, but that Mao should have been the hands-down winner, with his ledger easily trumping the European dictators’.

While these questions can devolve into morbid pedantry, they raise moral questions that deserve a fresh look, especially as these months mark the sixtieth anniversary of the launch of Mao’s most infamous experiment in social engineering, the Great Leap Forward. It was this campaign that caused the deaths of tens of millions and catapulted Mao Zedong into the big league of twentieth-century murders.

But Mao’s mistakes are more than a chance to reflect on the past. They are also now part of a central debate in Xi Jinping’s China, where the Communist Party is renewing a long-standing battle to protect its legitimacy by limiting discussions of Mao.

The immediate catalyst for the Great Leap Forward took place in late 1957 when Mao visited Moscow for the grand celebration of the fortieth anniversary of the October Revolution (another interesting contrast to recent months, with discussion of its centenary stifled in Moscow and largely ignored in Beijing).

The Soviet leader, Nikita Khrushchev, had already annoyed Mao by criticizing Stalin, whom Mao regarded as one of the great figures of Communist history. If even Stalin could be purged, Mao could be challenged, too. In addition, the Soviet Union had just launched the world’s first satellite, Sputnik, which Mao felt overshadowed his accomplishments. He returned to Beijing eager to assert China’s position as the world’s leading Communist nation. This, along with his general impatience, spurred a series of increasingly reckless decisions that led to the worst famine in history. ...