It's probably a fair bet that most Americans, if they can identify James A. Garfield as a president at all, would be hard put to place him where he belongs in the line of chief executives. Few if any presidents have left as faint an impression on public memory as he did during his brief stint in the White House, from March to September 1881.

With "Destiny of the Republic," a spirited tale that intertwines murder, politics and medical mystery, Candice Millard leaves us feeling that Garfield's assassination deprived the nation...