American Gun: A History of the U.S. In Ten Firearms by Chris Kyle, William Doyle

Army pipeline, and some commanders were even shelling out their own money to equip their units with the gun. One Colonel John T. Wilder of Indiana was so impressed by a field demonstration of Spencers that he lined up a loan from his neighborhood bank to buy more than a thousand Spencer repeating rifles for his “Lightning Brigade” of mounted infantry.
    Colonel Wilder’s commander was Major General William S. Rosecrans, whose Army of the Cumberland was tasked to rout the Rebs from Middle Tennessee. Though slow to move against Confederate General Braxton Bragg and his Army of Tennessee, once Rosecrans got moving he did so with style. In the last days of spring 1863, Rosecrans began a series of maneuvers that are still studied today for their near flawless execution. Wilder and his men, now armed with those Spencers he financed, were smack in the middle.
    The brigade was a one-off outfit, a hybrid of cavalry and infantry at a time when those two forces were very separate animals. Colonel Wilder was a bit of a different beast himself. Hailing from New York’s Catskill Mountains, he commanded a collection of infantry units totaling some fifteen hundred foot soldiers, along with a detachment of artillery. His first assignment was to run down a rebel cavalry unit that had made mincemeat of Rosecrans’ supply line. You don’t need to know much about combat to guess how that went; pretty much every horse I’ve seen is faster than any man I’ve met. Wilder came away from the assignment a wee bit frustrated.

Possibly a member of Colonel Wilder’s “Lightning Brigade” of mounted infantry—armed with a Spencer rifle.
Library of Congress
    But from that setback came a solution—he asked permission to mount his infantry. Wilder wasn’t transforming his brigade into horse soldiers. He wanted a force that could move at lightning speed, then dismount and fight. And when he said fight, he meant fight . Besides the repeaters, he armed his men with long-handled axes for hand-to-hand combat. Here was an officer who fully understood the phrase violence of action.
    Colonel Wilder also appreciated the meaning of the word charge , which is what he did on June 24, 1863, when tasked to take Hoover’s Gap, a key pass Rosecrans needed to outmaneuver his enemy. Wilder’s men slammed through the gap like a bronc busting out of its gate. They routed the 1st Kentucky Cavalry, then pushed well ahead of the main body of infantry they were spearheading.
    The Rebs counterattacked ferociously, sending two infantry brigades and artillery against the Northerners. Though badly outnumbered, Wilder’s men held their ground. The volume of fire poured out by the Spencers—nearly 142 rounds per man—was so large that the Confederates thought they were facing an entire army corps. The rebel lines collapsed into retreat.
    “Hoover’s Gap was the first battle where the Spencer Repeating Rifle had ever been used,” Wilder later wrote, “and in my estimation they were better weapons than has yet taken their place, being strong and not easily injured by the rough usage of army movements, and carrying a projectile that disabled any man who was unlucky enough to be hit by it.” He added, “No line of men, who come within fifty yards of another armed with Spencer Repeating Rifles can either get away alive, or reach them with a charge, as in either case they are certain to be destroyed by the terrible fire poured into their ranks by cool men thus armed. My men feel as if it is impossible to be whipped, and the confidence inspired by these arms added to their terribly destructive capacity, fully quadruples the effectiveness of my command.”
    One of Wilder’s soldiers wrote of the Spencer that it “never got out of repair. It would shoot a mile just as accurately as the finest rifle in the world. It was the easiest gun to handle in the manual of arms drill I have ever seen. It could be taken all to pieces to clean, and hence was little trouble to keep in