The greatest achievement of Donald Trump’s first 100 days as president was that there was a 101st. If things continue this way, he will finish out his term and then the nation, like someone after a boozy night, can right itself and get on with its business. We will restore the environment, repair alliances, recognize science, welcome immigrants, cherish honesty, value knowledge and return dignity to a White House where Jefferson may have dined alone but where Trump was joined by Sarah Palin. More than a fresh coat of paint is needed.

The passing of the first 100 days was simultaneously cause for mockery and relief — and both for the same reason: President Trump accomplished next to nothing. The courts held firm, so did much of the bureaucracy, and the press not only remains free, it has a new bounce to its step. Most of all, Trump seemed dazed by reality. All sorts of policies were pirouetted — China, Iran, Russia, Syria and Israel, among others — and Trump, like the junkie he is, scorned the news media while craving it dearly. He held it up like a mirror: Am I great? Am I pretty? Am I popular?

[Trump’s 100th-day speech may have been the most hate-filled in modern history]

And so the alarms have been muted. The Great Fascist Threat has receded, and it is considered both gauche and ahistorical to compare Trump to dictators of the past — you know their names. I quibble with that, because we can always learn from even extreme examples, but the Trump prototype that now seems most relevant is yet another German: Kaiser Wilhelm II. During his reign, World War I began.

That war, more than the greater one that followed, continues to intrigue historians because its cause is so hard to isolate. By Armistice Day, four empires were no more, about 17 million people were dead and the stage was set for a further calamity. But what started it? There are many explanations, but one factor, certainly, was the idiotic bellicosity of the German kaiser.

Anyone who turns to Christopher Clark’s book about the run-up to World War I, “The Sleepwalkers,” will recognize a Trump-like figure. The kaiser was a tweeter before his time, firing off letters, telegrams and orders without pausing to wonder about contradictions or policy or even common sense. (He demanded plans for invasions of Cuba, Puerto Rico and New York.)

“There can be no doubt about the bizarre tone and content of many of the kaiser’s personal communications in telegrams, letters, marginal comments, conversations, interviews and speeches on foreign and domestic themes,” Clark writes. “The kaiser spoke, wrote, telegraphed, scribbled and ranted more or less continuously.”

Clark then wonders whether “such utterances connected with the world of actual outcomes.” His answer is both frightening and reassuring. In the end, the kaiser was king but not dictator. He was considered a fool and widely ignored within his own government. Other governments had a harder time figuring him out. He often contradicted himself. He often seemed not to understand what he was saying, and he felt that he had no need to. “I am the foreign office,” he proclaimed. “I am the sole master of German policy.”

[Trump’s nifty plan to spend more and hurt poor people more — at the same time!]

My nifty likening of Trump to Wilhelm suffers from one compelling problem: The American president is much more powerful than the German kaiser ever was. Trump’s response to Syria’s use of the sarin nerve agent — swift but bracketed by contradictory policy statements — would not have been possible for Wilhelm. His ministers would have mulled it over, possibly blocked it — said “yes, sir,” clicked their heels — and then done nothing. (President Richard Nixon’s aides took the same approach to many of his harebrained schemes.) The kaiser benefited from a lazier technology. Mobilization took time, and a tomahawk was a hatchet, not a missile.

More disturbing than the similarities between Wilhelm of Prussia and Trump of Queens are their differences. The kaiser was the product of an archaic monarchical system — the bad luck of the draw. Trump, however, was elected in a democratic process, and yet the result has been distressingly similar. All Trump lacks is a pickelhaube, the familiar spiked helmet.

Whatever the cause of World War I, it is clear that the Europe of 1914 needed stability. The arrangements of the 19th century were crumbling, Germany and Britain were warily eying each other, and the Ottoman and Austro-Hungarian empires were coming apart. The kaiser, with his chaotic mind, was only making things worse. The world needed consistency, clarity, wisdom — instead, it got the juvenilia of a deluded leader. Not much has changed.