At the same time, Mr. Kander’s military experiences, and their psychological aftermath, were undercutting his ability to function. Close friends and supporters started to notice, but said nothing. “I saw him every day, and saw his symptoms, and didn’t do anything about it,” Mr. Rakov said with regret.

Military service has long been a steppingstone to a political career. But whether they fought at Kip’s Bay or Khe Sanh, political leaders have rarely been open about the aftereffects of combat.

Was George Washington jarred awake on winter nights by the memory of horses shot out from under him or musket balls passing so close that they ripped his coat? Was President Rutherford B. Hayes haunted by the memory of lying wounded in no man’s land while the men of his Union Army brigade fell around him? Was Senator George McGovern troubled by the 30 bombing missions he flew during World War II, including the time his B-24 caught on fire and nearly crashed? If they were, they did not say so on the stump.

Few politicians have had to navigate this minefield quite like Senator John McCain, who was held prisoner and tortured for years in North Vietnam. The senator, who died last year, suffered permanent physical injuries, but said he had emerged essentially unscathed psychologically, except for an aversion to the sound of jangling keys, which reminded him of his jailers.

“I pressed him on it,” his longtime aide and biographer Mark Salter said in an interview. “‘Nothing? You got nothing? Nothing keeps you up at night?’ He said no. He said he had left it all behind him.”

Even so, Senator McCain was hounded during two presidential runs by whisper campaigns claiming that his years as a prisoner had made him erratic and unfit for office, even after he released thousands of pages of medical records to the news media to support his denials.

Over more than 30 years in the Senate, Senator McCain never spoke in depth publicly about the mental toll of his war experience. Neither did his peers.