In the days following Lee’s surrender at Appomattox Court House, word had spread that Union troops were seizing good horses. Garland had hidden Don Juan at a farm in the woods on behalf of its owners, but another freedman told the soldiers where to find it. ... For 150 years, it has been public knowledge that Custer owned Don Juan, but not how he acquired it. His many biographers have written that Union troops seized it during a wartime campaign, as they confiscated every horse in Rebel territory; that was Custer’s own explanation. Until now, the truth has remained hidden in the open, told in correspondence and affidavits archived in the library of the Little Bighorn Battlefield National Monument and the National Archives that have aroused little curiosity among those biographers. But the truth raises important questions about the man and his place in American history. ... And 16 days after Lee’s surrender, ten days after Lincoln’s death by assassination, with all fighting at an end east of the Mississippi River, George Armstrong Custer stole a horse. ... Was it greed that corrupted him? A passion for fine horseflesh—common to most Americans in 1865, but particularly intense in this cavalryman? Was it power—the fact that he could take it? As the military historian John Keegan memorably wrote, “Generalship is bad for people.” Custer was only 25, an age more commonly associated with selfishness than self-reflection, and perhaps that explains it. But the theft was not impulsive. It had required investigation, planning and henchmen. It may help explain his self-destructive actions in the months and years that followed.

The verb to use in polite company is “cover.” The stud covers the mare. Or: About 11 months after she was covered, the mare gave birth to a healthy foal. ... The deed itself, here in the hills of Kentucky horse country, is governed by strict rules. Section V, paragraph D of The American Stud Book Principal Rules and Requirements is clear: “Any foal resulting from or produced by the processes of Artificial Insemination, Embryo Transfer or Transplant, Cloning or any other form of genetic manipulation not herein specified, shall not be eligible for registration.” No shortcuts, no gimmicks. All thoroughbreds must be the product of live, all-natural, horse-on-horse action. ... two weeks after American Pharoah retired, his 2016 stud fee was set at $200,000, the highest ever for an unproven, first-year stallion. Only one other active stud—a tested, 15-year-old veteran named Tapit—commands that much per successful cover. Tapit’s first-year fee was $15,000; his rate rose to its current $300,000 only after a decade of producing stakes-winning foals. ... Successful stallions are routinely matched with more than 100 mares in a five-month breeding season. Particularly energetic ones might cover as many as 200 a year. If American Pharoah produces several seasons of healthy and fast foals, standard pricing norms suggest that his stud fee will multiply exponentially. Very quickly, the $8.6 million he earned during his racing career would begin to look like small change.