WWII: Tanks
The mechanical juggernaut on the field of battle has captured our imagination for years and during WWII these steel beasts were a lethal and tactical necessity to force the opposition into capitulation. "In a man to man fight, the winner is he who has one more round in his magazine."-German field Marshall Erwin Rommel. It might help if you have a whole lot of armor between you and that last round as well...