In 1966, Mao Zedong had a problem.

The Chinese leader who had led a peasant army to victory in the Chinese Civil War, and established the communist People's Republic of China in 1949, was getting old.

Worse, his radical policies had devastated the country, and triggered the deadliest famine known to human history.

By the early 1960s, Mao's once-great influence and public presence were at an all-time low, and there were rumors that he was dying, or even dead already.

He needed to find a way to seal his legacy as the face of Chinese communism.

And a new revolution to lead.

It started in a river.

-The Great Leap Forward was a disaster. [Chapter one: Mao loses his grip.]

It was Mao's 1958 plan to quickly industrialize China by working its massive peasant population nonstop.

He promises to transform the People's Republic into an instant paradise through the sheer force of numbers.

Forcing workers in the countryside to farm crops on government-run communes.

And millions more to manufacture crude steel in homemade blast furnaces.

And even though Mao told the world that the plan was succeeding…

Everywhere, the communists report, production records are being broken.

The truth was much more desperate.

They flood the fields, exhaust the soil, and farm production instead of going up, goes down.

The Chinese people were being forced to work tirelessly on land they once owned themselves and they were starting to lose morale.

And despite reports of widespread famine, with millions of people starving to death, Mao kept production quotas high.

The pace grows more frantic.

Ceaselessly, without rest, one observer writes.

"The countryside is in convulsion.".

Mao's Great Leap Forward ended in 1962.

By that time somewhere between 23 and 55 million people had died in the famine.

Over in the Soviet Union, a different political upheaval was happening.

Soviet leader Joseph Stalin, who Mao modeled himself after, was dead.

And Mao watched as Nikita Krushchev, Stalin's successor, implemented a period known as "de-Stalinization.".

Where Krushchev set out to reverse many of Stalin's policies and dismantle the personality cult that had formed around him.

Mao saw his own legacy potentially suffering the same fate.

His communist revolution was long over, and his ideas weren't taken as seriously after the disaster of the Great Leap Forward.

It was starting to look like Mao's place in the pantheon of powerful communist figures, like Vladimir Lenin and Karl Marx, was in peril.

This is where the river comes in. [Chapter two: the swim.]

Mao had a reputation for being a strong swimmer.

And even used it as a symbol of his ideology.

In 1956, he swam across China's biggest river, the Yangtze, in three highly-publicized swims.

To demonstrate that big things, like U.S. imperialism, didn't intimidate him.

10 years later, Mao took on the Yangtze again, to dispel rumors of his failing health.

This time with cheering crowds swimming alongside him.

He brought his personal photographer, who snapped this photo of the aging dictator in the river.

And another one showing Mao waving to his fellow swimmers, with the landmark Wuhan Yangtze River Bridge behind him.

An iconic architectural achievement of the communist government, and proof that he was at the Yangtze.

The swim made the front page of China's state newspaper, reporting that Mao swam around 15 kilometers, a little more than 9 miles, in a span of 65 minutes.

Which meant the 72-year-old would have shattered world speed records.

A lot of people outside of China laughed at the outlandish story, but some saw the swim for what it was: a sinister sign.

Pointing out that Mao's swims from a decade earlier preceded the catastrophic Great Leap Forward.

Experts feared that Mao was on the verge of kicking off another disastrous period of turmoil in China.

They were right.

Two months before the swim, Mao had announced the beginning of his Great Proletarian Cultural Revolution. -[Chapter three: the cultural revolution.]

A call to hunt down and eliminate the "bourgeoisie who had sneaked into the party.".

Basically to purge the government of anyone who strayed from principles of Maoism.

And it kicked into high gear after his historic swim.

Which prompted a craze for swimming in China, but more importantly, a craze for Mao.

Especially among the group that Mao wanted to influence the most: China's youth.

Writer Liang Heng recalled that seeing Mao as "human flesh and blood" after the Yangtze swim resolved him to "serve him with all his heart.".

Millions of Chinese youth organized into the fanatical Red Guards, a paramilitary force concentrated mostly in Chinese cities.

And, with Mao's blessing, they wreaked havoc in the name of Cultural Revolution.

Their mission was to destroy the Four Olds.

Old culture.

Old ideology.

Old customs.

Old traditions—all of the olds must be destroyed.

The idea was basically to tear down the vestiges of imperial China and rewrite history centered around Mao Zedong.

Renaming buildings and streets, destroying cultural sites, and violently humiliating, and often torturing and murdering, anyone they accused of opposing Mao's ideas.

Which they plastered all over the cities.

And carried in their pockets in the form of Mao's Little Red Book, a collection of his sayings and principles.

And although the violent Red Guards were basically dissolved by 1969, the Cultural Revolution is considered to have continued until Mao's death in 1976.

Ending a decade of destruction that had elevated the leader to god-like levels.

And resulted in over one million people dead.

The chaos of the Cultural Revolution scarred China for generations.

But Mao basically got what he wanted.

Even though the Chinese Communist Party condemned the Cultural Revolution in 1981, and Chinese communism diverted away from Maoism, they didn't denounce Mao himself.

The Cultural Revolution solidified Mao's cult of personality, and that influence has lasted.

Mao's swim, which is still commemorated each year in China, was more than a display of strength.

It was a message: to get behind Mao as he began his last revolution.