The Ivanka Trump of pre-Civil War America, Harriet Lane dazzled Americans using the technology of her times: mastering the daguerreotype and the telegram rather than the Internet and Instagram. As the glittering, petticoated star of a beleaguered White House, she charmed princes and populists, the press and the public. Yet, ultimately, all her girl power couldn’t save her uncle James Buchanan’s pitiful presidency.

Lane’s style was just risqué enough to enhance her legend without destroying her reputation. Beyond the glitz, this first woman to be called “first lady” in print contributed helpful politicking, wise advice, and a popularity boost to the Buchanan presidency. But, like Ms. Trump, Miss Lane was not married to the man she called “Nunc” and others called “Mr. President.”

Fellow mourners’ anguished solitude reinforced the natural solicitude James Buchanan had for his niece Harriet, born on May 9, 1830. By the time she turned eleven she had lost both her parents. While mourning his sister, Buchanan remained haunted by the great loss of his life, when the great love of his life, Anne C. Coleman, died. This tragedy in 1819, shortly after Buchanan abruptly ended their engagement, triggered speculation that she killed herself. The pain he lived with constantly, occasionally burst through the portly Buchanan’s genial veneer. Although he loved his “adopted daughter,” he could be curt and controlling, monitoring her mail and shaming her for serving a bad meal. Insisting she follow his “advice” before getting engaged, and warning only to marry someone who can “afford you a decent and immediate support,” the brokenhearted Buchanan explained: “In my experience I have witnessed the long years of patient misery and dependence which fine women have endured from rushing precipitately into matrimonial connections without sufficient reflection.”