In December 1919, US president Woodrow Wilson gave his friend and prominent banker Thomas Lamont a secret mission: go to China and persuade the warring Chinese to end their civil strife and accept a two-China proposal.

Despite their best efforts, the mission to divide China would fail, as have all others before or since. Now US President Donald Trump has signalled he might want to give it a try, but if so, history proves he has a very steep hill to climb.

Wilson, a visionary statesman, meant well almost 100 years ago. He hoped to reconcile the differences between two rival governments struggling to control the whole of China. Ever since the 1911 revolution, the once-great Asian empire had been divided between a military government in Peking (Beijing) and a nationalist one in Canton (Guangzhou), with several warlords each occupying land the size of a European country in between.

The American president was eager to stop the fighting. China had the world’s largest population, but the civil war endangered millions of people and denied the country a chance to develop its economy. It also made China easy prey for its predatory neighbours Russia and Japan.

Wilson wanted bankers to help China by financing the modernisation of its industry. But no banker would provide loans to a nation without knowing who would be the ultimate guarantor of debt. Ending the civil strife would be a crucial first step, Wilson reasoned.

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The quickest way was to persuade the two governments to accept reality and settle for what they had. Even if divided, each China would still be larger than most nation-states in the world. There were also significant political, cultural and even linguistic differences between the north and the south.Wilson asked Lamont, a senior partner at J.P. Morgan: is it possible to have two Chinas?

Lamont was a perfect candidate for the task. In the days preceding the establishment of the International Monetary Fund and the World Bank, the leading man of J. P. Morgan was no common Wall Street banker – he was a statesman financier with tremendous power. Lamont was well-versed in diplomacy. He represented the US in the negotiations of the Treaty of Versailles after the first world war.

In 1920, Lamont sailed to the Far East. He first arrived in Shanghai to see Dr. Sun Yat-sen, head of the nationalist government in southern China. Educated in Hawaii and Hong Kong, Sun was a fluent English speaker. Lamont asked Sun if peace could be achieved between the two Chinas but was shocked by his reply. “Peace between the south and the north?” Sun repeated the question. “Why, yes. Just you give me US$25 million, Mr Lamont, and I’ll equip a couple of army corps. Then we’ll have peace in short order.”

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Lamont was equally frustrated by his trip to Peking. The military government headed by Hsu Shih-chang (Xu Shichang) would not hear any suggestion to divide China. Hsu only wanted to secure American loans.

Reporting back to Washington, Lamont recommended no Chinese loans to be made until the country was unified. Two years later, Lamont formally asked Secretary of State Charles Evans Hughes to disband the China consortium – a group of American bankers formed at the urging of the White House for the possible China venture.

The first attempt to persuade the Chinese to accept a divided China ended in failure. Twenty-eight years later, in 1948, US president Harry Truman and Soviet leader Joseph Stalin tried their hands again. This time, China was torn by a showdown between the Communist forces led by Mao Zedong (毛澤東) and the nationalist government under Chiang Kai-shek. The communists, backed by the Soviets, scored decisive victories and carried the north. Chiang, a long-time American ally, tried desperately to regroup in the south for a counterstrike. Both Washington and Moscow wanted to contain the conflict, fearing they would be dragged into a direct war.

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With their confidence in Chiang badly shaken, the Americans tried to force the generalissimo into retirement and replace him with a more moderate Li Tsung-jen. American ambassador John Leighton Stuart first proposed the idea to Secretary of State George C. Marshall in October 1948. Marshall and Stuart hoped that by forcing out Chiang, they could initiate peace talks to end the war and give the nationalist government a chance to hang on to the south.

The Soviets also cautioned Mao not to push his offensive to a complete victory, claiming it would risk a direct confrontation with the US. Stalin admitted to Yugoslav communist veteran Vladimir Dedijer in 1948 that “it would be better to have a China divided along the Yangtze River than risking another world war for its unification”. In January 1949, Stalin dispatched Anastas Mikoyan to tell the Chinese communists the Soviet preference to see China divided along the Yangtze. He also sent Nikolai Roshchin to Nanjing ( 南京 ) to sound the nationalists out.

Both Mao and Chiang were incensed by the pressure from Washington and Moscow. Chiang briefly stepped down and the two sides engaged in half-hearted peace talks. Before long, the war renewed.

Mao’s armies swept across the Yangtze and drove the remaining nationalists to Taiwan. The attempt by the US and the Soviets to divide China, however, left long-lasting implications. Chiang bitterly blamed the Americans for the defeat. Till his death, the generalissimo never gave up his dream of retaking the mainland. Mao, on the other hand, grew suspicious of Soviet intentions. He believed Stalin was seeking to keep China divided and weak. This sowed the seeds of the Soviet-China split decades later.

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Sun, Hsu, Mao and Chiang had very different personalities, backgrounds and political convictions. Between 1920 and 1948, China was weak and anarchic. It seemed more likely to break into pieces than becoming a unified nation. Yet all of them were offended by the idea of a divided China – regardless of how good the intention was.

Nationalism certainly played a big part. It was the most important force in China’s transformation from an empire civilisation into a nation state. All Chinese political leaders after the 1911 revolution were first and foremost nationalists, regardless of their political convictions. But the Chinese obsession with political unity, or Dayitong, could be traced back much earlier.

Centuries before the first emperor Qin Shi Huang established a centralised empire in China in 221BC, the Chinese had already developed and embraced the idea of political unity. It is a common mistake to say Emperor Qin was the first one to unify China. More correctly, he was the first one to unify China under a centralised government. The two preceding dynasties before Qin – Shang (1600 to 1046BC) and Zhou (1046 to 256BC) – ruled China under a feudal overlord system. All their rulers’ claims of sovereignty over the entire Chinese civilisation were accepted by feudal lords.

In fact, this is how a Chinese sovereign power derives its mandate and legitimacy. It is the ultimate guarantor of law and order, protector of the civilised world against barbaric forces and keeper and promoter of Chinese culture. Any claim from another party to that role would instantly weaken and challenge the political legitimacy of the power-holder. During the Warring-States period between 475 and 221BC, all seven kingdoms held territory bigger than the medieval kingdoms in Europe.

Yet none was willing to declare independence from their overlord, the House of Zhou, whose holding had already been reduced to a puny pocket of land. Doing so would immediately turn the kingdom into a barbaric power and make it a fair game for joint attacks by the rest.

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The idea of political unity is deeply ingrained in the DNA of Chinese civilisation and mentality. While China has gone through cycles of unification and division throughout history, few political leaders would publicly give up unification as the ultimate political goal. This way of thinking may be ancient, but it still looms large in the consciousness of most Chinese today.

Some may criticise such political logic and question its validity. Yet to paraphrase Kunming (昆明) native and scholar Benedict Anderson, all political communities are imagined, but that does not make them unreal. People are willing to die for such imagined communities because of their profound emotional hold.

Today, China is facing a new challenge as the people of Taiwan develop a very different kind of imagined community. How to resolve the incompatibility between the two territories will test the wisdom of the Chinese people and their leaders. But it would be overly simplistic to dismiss China’s obsession as a pure territorial ambition. Emotionally and politically, Taiwan means more to China than Crimea to Russia. No Chinese government, no matter under what political system, could hope to retain its political legitimacy if it gives up on unification.

President Trump is the latest world leader to challenge the notion of a unified China. Or maybe he just sees it as a bargaining chip with Beijing. It is easy to see where Trump comes from: He is looking for low-cost leverage in Sino-US negotiations. But the president may well have underestimated the complexity of the issue.

Political greats like Wilson, Truman and Stalin all tried their hands and got burnt. If Trump can persuade the Chinese to give up the idea of political unity, he will truly go down in history as a game-changing president.

Chow Chung-yan is executive editor of the South China Morning Post, overseeing daily print and digital operations