The tank. The British Mark I (above) was the world's first combat tank. Slow and highly unreliable, the first tanks were used primarily to assist in trench warfare by breaking through barbed wire defenses. 49 tanks were available for the battle, though only half those were mechanically sound enough to be operated.

Chad Vander Veen  | 

Chad Vander Veen previously served as the editor of FutureStructure, and the associate editor of Government Technology and Public CIO magazines.