Sustained mobility was the game-changer of 20th-century warfare. Such a formation could travel 50 miles or more per day, and then repeat the process day after day, out to the limit of its logistical network. A mechanized formation formed around a hard core of swiftly moving tanks, surrounded by vehicles of all sorts to perform the reconnaissance, carry the infantry and drag the guns, the Panzer division brought the concept of sustained mobility to modern warfare. The new gang had a name: the Panzer division.

They swept all before them, raiding and pillaging, humiliating the local authorities, and shooting down anyone who got in their way. A new gang did indeed ride into town-grim riders eager for vengeance. World War II was no movie, but the first two years of the war followed the above script precisely. Cowards flee, mothers hurriedly grab their children, and the sheriff desperately tries to round up a few good men. They're armed, they're mounted, and they're mean. Hollywood westerns often feature a stock scene where the new gang rides into town.

Modern day tank divisions