Seeing that the boy was in blue uniform, the sentinels did not make even a futile effort to detain him. Not until he had whirled past in a cloud of dust did one of them belatedly recall that the horse’s saddle had borne in brass the letters “C. S. A.,” instead of “U. S. A.” And he and his comrade fell to speculating bewilderedly as to why a small-boy courier in Union uniform should happen to be riding on a Confederate cavalry saddle. On galloped Jimmie, giving the dust to the few riders and pedestrians, who now began to appear on the white turnpike. Into Frederick and through its unpaved, rutted main street galloped the lad. The street through which, less than a week earlier, Stonewall Jackson had led his dusty legions. From an upper window of one of the thoroughfare’s wooden houses (according to a tale as apocryphal as it was dramatic) aged Barbara Frietchie had waved the bullet-ridden stars and stripes and by her gallant loyalty had touched the chivalric Southern chief’s heart. The sole basis for the Barbara Frietchie legend, moreover, according to Jackson’s own tale and his staff’s, was this: As the Confederate swung down the street two little girls, each waving a tiny American flag, ran out from the sidewalk and shook their flags defiantly--almost in Jackson’s very face--whereat, instead of fiercely ordering the flags to be fired on, Jackson had turned to one of his aids and smilingly commented: “We don’t seem to be especially popular here.” Jimmie, who had heard of neither the fact nor the more inspiring legend, dashed on, looking neither to right nor left. His horse, wholly unaided by the rider, eluded the scant traffic of the street and saved Jimmie from more than one bad collision. Pedestrians scattered to left and right before the thundering hoofs and yelled angry warnings after the fast-disappearing horseman. Mounted military men drew to one side and laughed aloud at the scarlet-faced little figure bunched over on the withers of the great charger. Through the street and beyond galloped Jimmie. He drew up at last (with a suddenness that sent the horse back on his haunches and the rider well-nigh over his mount’s ears) in front of a house whose walk from porch to road was patrolled by a sentinel. On the veranda lounged several gaudily attired staff officers. From the porch roof jutted a white flagstaff, gold-eagle crowned, supporting a huge silken American flag. A quarter-mile away that morning Dad had pointed out the house to his grandson as temporary headquarters of Major-General George Brinton McClellan, commander of the Army of the Potomac--a leader who partly for the sake of his middle name had always held Jimmie’s admiring curiosity. Off the horse scrambled the boy, his body aching all over, and his short, cramped legs all but doubling under him. Through the gate he lurched and up the path. The sentinel halted him before he had taken three steps.