The humiliating demise of Jeb Bush's presidential candidacy resulted from his willingness to make himself a sacrificial lamb to save the Republican Party from Donald Trump. It remains to be seen whether anyone else will so conspicuously offer himself.
None of the other GOP candidates seemed quite as personally offended as Jeb Bush was by Mr. Trump's effrontery, aimed as it so often was at Mr. Bush and his family.
Trump's mockery of Jeb's "mommy" for campaigning for him in South Carolina, and his suggestion that George W. Bush lied about the existence of weapons of mass destructions to justify his invasion of Iraq, challenged the integrity of the whole Bush family. It finally seemed to arouse Jeb's exclamation point!
But Jeb's own laid-back manner and style, unlike the swagger and cockiness of his brother, made him a perfect target for the loud-mouthed bully-boy from Manhattan. The label Mr. Trump slapped on Jeb -- "low energy" -- appeared to leave him figuratively gasping for breath.
For a time, though, Jeb tried his best. He spent a lot of money and spoke the truth about the outsider's crudity. But Jeb's own placid personality, his blueblood family line and Mr. Trump's special talent for character assassination all brought him down, leaving him with a poor fourth-place finish in the South Carolina primary.
Early in the campaign season, Mr. Bush launched a fundraising "shock and awe" campaign designed to blow away other contenders; the intention was to sew up the nomination for Jeb before the race ever started. The campaign's masterminds adopted as its logo "Jeb!" -- perhaps in keeping with his plan to campaign "joyfully." But almost from the start, there was little to be joyful about.
Jeb could have anticipated that his brother's 2003 invasion of Iraq would open the floodgates to political troubles for his candidacy. Yet when he was asked on a television show last May whether he would have followed his brother's path, Jeb said he, too, would have invaded.
As critics and foes leaped on him, he claimed he had misunderstood the question. Had he known at the time that Saddam Hussein did not have the weapons of mass destruction, he said would not have chosen to invade Iraq.
As a first-time campaigner for national office, Jeb proved to be halting and uncertain. He sought through most of 2015 to downplay his ties to his father and brother, arguing that he was his "own man" running on his own record as a successful two-term Floridagovernor. But finally he called on George W. to come to the rescue, to no avail.
Jeb's strategists did not gauge the dynamic entry into the Republican race of hard-edged and take-no-prisoners competitor Donald Trump. The celebrity candidate methodically took aim at the younger Mr. Bush, whose rather Marquis of Queensberry style offered an easy target.
Mr. Trump cuttingly and effectively portrayed Jeb as a man who was not up to the rough-and-tumble rigors of a presidential campaign. In speeches and in debate encounters, Bush came off as ineffective. When he finally undertook to be the most consistent and pointed critic of Mr. Trump's bare-knuckle tactics and verbal abuse, he was too late, suffering Mr. Trump's most telling punishment, and his campaign collapsed.
In retrospect, the Jeb Bush strategists underestimated both the influence of Trump's personality and his angry, brutal message, built of smidgeons of Huey Long, Joe McCarthy, George Wallace and other strands of populist, anti-elitist hostility long in the dark corners of American politics.
Jeb Bush's attempt to confront it, in pursuit of his own political purpose, also bore elements of restoring today's politics to the more civil and laudable standards of conduct and discourse in better days not too far distant. The nation can only hope it has not seen the end yet of that quest, as Mr. Trump's scorched-earth tactics and rhetoric plunge toward his undefined goal of "making America great again."
Jules Witcover's latest book is "The American Vice Presidency: From Irrelevance to Power," published by Smithsonian Books. You can respond to this column at firstname.lastname@example.org.