Erastus Blakeslee

Blakeslee did not invent the Spencer Carbine, he just made it more convenient to use.
Repeating weapons effectively increased the ability of the Cavalry to defend itself. Federal Cavalry came to be armed with more effective repeating weapons [like the Spencer] as the war progressed. Confederates were equally inventive, but their manufacturing facilities -- already strained by war production -- just could not master the production of non-reusable metallic cartridges.

Federal authorities feared that repeating weapons would cause soldiers to expend their ammunition too quickly and out run their supply. Blakeslee addressed the need for troopers to carry large quanties of ammunition with them with the introduction of the "Blakeslee Box."