The writer is a partner at Sequoia Capital

As events unfold in Washington, I have been thinking about my grandfather who, just over a century ago, fought for the German army at Verdun. That battle, the bloodiest of the first world war, lasted about as long as the US presidential election campaign and was fought to a stalemate even though it cost 750,000 casualties. The unexploded shells lying just beneath the surface of this patch of France still claim lives and much of the area on which the armies fought is too poisoned to be farmed or occupied.

But it is the political environments created by the 1914-18 conflict, and by the 2020 election campaign, that warn of greater dangers today.

When, at the end of first world war, my grandfather returned to his job as a magistrate in Munich, he hoped that life would return to normal. Yet, after living through the Spanish flu pandemic, the messy creation of the Weimar Republic, the ruinous hyperinflation there and the Depression, he discovered that the demons unleashed between 1914 and 1918 had only gained in strength.

As a Jew he lost his job in 1933, was imprisoned in Dachau and later, after the borders in Europe had been closed and he had been denied entry to the US, was shipped to the Piaski ghetto and murdered.

In today’s US, following certification of the election result, it is tempting to think that peace will break out, and support for extreme views will dissipate. But here, too, there may be no easy return to normal.

If Donald Trump had collected about 43,000 more votes out of 160m — in the right states — the chances are that he would be starting his second term next week. If 25,000 votes had gone the other way in the Georgia Senate run-offs, his party would have retained blocking powers over the legislative agenda. And the 147 US lawmakers who cast votes objecting to the election result promise more ugly times ahead.

So, now, it’s up to all of us in the world of business to play our part and make sure the extremism of both left and right in America is seen for what it is: a menace to our future together.

We are all culpable. Some of us were ineffective with our warnings. Some provided support to forces of darkness. But all of us are guilty of not listening closely enough to the arguments of our opponents.

Almost five years ago, I tried, in vain, to highlight for the business community Mr Trump’s past as a conman, bully, racist, failed entrepreneur and authoritarian. I also wrote about the differences between him and the people who start Silicon Valley companies, noting: “They are not nationalists who stir up dark memories of purges, pogroms, the 1930s, Latin-American strongmen or central African dictators.”

Many businesspeople scoffed at this portrait of Mr Trump — preferring to support him because they liked many of his policies.

Their arguments always reminded me of the Prussian military leaders and German business magnates who thought they could control the dark tendencies of an army corporal turned political strongman in the 1920s. They did not understand what could happen when the principal communication channels are commandeered, the press denounced, the judiciary belittled, and laws undermined.

Thank goodness Mr Trump has not yet had the managerial self-discipline to turn the Proud Boys into brown-shirted militias.

During the past four years, it has been more expeditious for many business leaders to act like “Collabos” — as the French dubbed their countrymen who colluded with the Germans in the second world war.

Let’s hope that events in the US last week persuade them to have a change of heart. They may find it useful to remember that in 1923 Adolf Hitler led a failed coup and was briefly imprisoned, and subsequently manipulated his growing popularity to seize supreme power 10 years later.

The past four years have demonstrated there are times when it is best to set self-interest aside. Given the choice between appealing policies and a dark character, and objectionable policies and a respectable character, it is always safer to pick the latter.

All I hear now, as impeachment looms again, are echoes of a childhood growing up in Britain and the refrain of my parents, both refugees from Nazi Germany: “If it did happen, it can happen. If it did happen there, it can happen here.”