Our very own history surprisingly serves as a prologue for how mercurial Donald Trump is acting and behaving nowadays.

How is that possible? It is because Trump derives inspiration from a mediocre and obscure American President who happens to loom large in our history.

That ghostly President haunting Trump is William McKinley, the 29th US President behind the brutal Filipino-American war and the 1898 “benevolent assimilation” doctrine that laid out how the American colonizers were to govern us.

Now, some present-day American political observers believe Trump wants to be the modern McKinley.

Trump himself isn’t shy about saying so. “President McKinley made our country very rich through tariffs and through talent. He was a natural businessman,” Trump once trumpeted. He has since repeated versions of his claim.

Few observers, however, have “grasped the real significance of Trump’s remarks,” says American historian Alfred W. McCoy, who has written five or so books on Philippine affairs.

“To correct such critical oversight,” says McCoy, “it’s important to ask two significant questions: Who was William McKinley and how might his legacy influence current American policy?”

Now, the big issue which the assassinated McKinley was known for — first as a congressman and then as president from 1897 to 1901 — was record-high protective tariffs or taxes on imported goods.

High tariffs also presently defines protectionist Trump. His recent wild on-and-off tariff threats are not only roiling the US but also other countries.

Republican McKinley too won election thanks to the machinations of one 19th century wealthy industrialist who, as one commentator says, strikingly resembles “tech bro” billionaire Elon Musk.

The 1890s in America was known as the “Gilded Age” and was a period of robber barons, extreme wealth disparity, and protectionist tariffs. And Republicans then, says one American commentator, “were in bed with rich industrialists and President McKinley was their guy.”

Isn’t that eerily similar to the relationship between present day Republicans, tech bros, and the second Trump presidency?

Anyway, an economic depression marred McKinley’s presidency, which could also be the fate of the Trump reality-TV presidency if it can’t properly manage tariffs in an age of interlocking economies.

But Trump seems to ignore that alarming prognosis. He instead is attentive to McKinley’s imperialist agenda — which had engulfed us.

Under McKinley, the United States became an empire. He used the brief Spanish-American War of 1898 — fueled partly by an earlier version of fake news called “yellow journalism” — to seize a colonial empire of islands from Puerto Rico to the Philippines. A “manifest destiny” that starkly resulted in the massacre and torture of thousands of Filipinos.

At any rate, McCoy says, “Trump and his key advisers are planning to use McKinley’s Gilded Age imperialism as their guide, even their inspiration, for overturning the liberal internationalism that has marked American policy for the past 80 years.”

This contention is said to inform Trump’s bellicose comments regarding Greenland and Canada.

Annexing Canada as the 51st state, by the way, isn’t Trump’s original idea. During McKinley’s time, Republicans spectacularly failed to annex Canada.

Anyway, Trump’s attempts to return to the great-power politics of the Victorian age — indicated by his penchant for dealing privately with “peer autocrats” like Russia’s Vladimir Putin and China’s Xi Jinping rather than consulting with American allies — means Trump is radically remaking the American foreign policy of the past 80 years.

Such an epochal change, says McCoy, means “likely to be not just the end of the liberal international order but the accelerated decline of US global power which had, over the past 80 years, become inextricably interwoven with that of free trade, close alliances and rules of inviolable sovereignty.”

A dire prospect that will likely trigger worldwide uncertainties and instabilities that won’t spare our little corner of the world.