History is littered with environmental disasters, but few compare to the one kicked off in 1958 in China. That was the year that Mao Zedong, the founding father of the People's Republic of China, decided that his country could do without pests like sparrows. The impact of this ill-conceived decision — along with many other policies he put in place — caused a domino effect of destruction. Three years later, as many as 45 million people were dead.

How did this happen? It all started nine years after the Communist Party of China took power. That year Zedong initiated what he dubbed the Great Leap Forward, a massive social and economic campaign that, among many other things, turned farming into a collective, state-sponsored activity. Individual, private farming was banned as part of China's transformation into a communist system.

One of Zedong's first actions after collectivizing agriculture was probably intended to protect the farms. Sparrows, he was told, ate a lot of grain seeds, so Zedong ordered the people to go forth and kill all the sparrows. During the Great Sparrow Campaign, as it has been called, hundreds of millions of sparrows were killed, mostly because people chased them until the birds were so tired that they fell out of the sky. (The campaign was part of the broader Four Pests Campaign, which also targeted rats, flies and mosquitoes — all with the aim of improving human hygiene.)

The problem with the Great Sparrow Campaign became evident in 1960. The sparrows, it seemed, didn't only eat grain seeds. They also ate insects. With no birds to control them, insect populations boomed. Locusts, in particular, swarmed over the country, eating everything they could find — including crops intended for human food. People, on the other hand, quickly ran out of things to eat, and millions starved. Numbers vary, of course, with the official number from the Chinese government placed at 15 million. Some scholars, however, estimate that the fatalities were as high as 45 or even 78 million. Chinese journalist Yang Jisheng, who chronicled the famine in his book "Tombstone," estimates the deaths at 36 million people. (The book, published in the U.S. last year, is banned in China.)

But the people did not go down quickly or easily. "Documents report several thousand cases where people ate other people," Yang told NPR last year. "Parents ate their own kids. Kids ate their own parents." The behavior was so awful — with thousands of people murdered for food or for speaking out against the government — that the topic of what has become known as the Great Famine remains taboo in China more than 50 years later.

Perhaps the most tragic aspect is that most of those deaths were unnecessary. Although the fields were empty, massive grain warehouses held enough food to feed the entire country — but the government never released it.

A series of tragedies

The deaths of the sparrows were not the only contributing factor to the famine, murders and deaths. For one thing, there was a massive drought in 1960. For another, the central government instituted new agricultural practices that proved to be complete failures. At the heart of it, the real cause was the Communist government, which — either as policy or by the selfish act of various officials — kept the grain from being delivered to those in need and covered up the problem. They also ruthlessly, sadistically and brutally detained, beat and hunted down anyone who appeared to question the situation.

China has continuously played down the causes and effects of the Great Famine, which is still officially known as the "Three Years of Difficult Period" or "Three Years of Natural Disasters." Yang told The Guardian last year that the full truth may never come out in mainland China, at least not officially. "Because the party has been improving and society has improved and everything is better, it's hard for people to believe the brutality of that time."

But the story is leaking out. Yang told NPR that the book has been counterfeited and the e-book pirated in China, something he doesn't care about. "Our history is all fabricated. It's been covered up. If a country can't face its own history, then it has no future," he said.

The Great Sparrow Campaign was the start of the greatest mass starvation in history
In 1958, Mao Zedong ordered all sparrows to be killed. As a direct result, millions of people starved to death.