From The Manufacturer/Wikipedia/People Smarter Than Us:
Invented in the late 1850s by Benjamin Tyler Henry, this revolutionary lever action repeating rifle was the most important firearm of its time and went on to become the most legendary American firearm of all time. Patented in 1860 and first used during the Civil War, the rifle’s rapid fire capability and high-capacity tubular magazine stood in amazing contrast to its single-shot musket counterpart. It became known as the rifle you could “load on Sunday and shoot all week long.” After the war, the Henry rifle headed west and went on to play a significant role in the homesteading of that great frontier.