Warfare is constantly changing, with militaries advancing their weaponry as fast as technology and budgets allow, and it has been this way throughout the entire history of man. But the battlefield has never changed as quickly as it has over the past 150 years, going from cavalry charges to drone strikes in a flash of time, when compared to the grand span of history. Several firearms were key to the evolution of warfare over the past century-and-a-half—here’s a look at five guns that changed modern warfare forever.