Cannons.

Cannons have fired balls of iron and atomic bombs, changed the way wars are fought, and now come equipped with smart weapons. Beginning with 13th-century cannons that were designed to penetrate forts of the day, we'll see how cannons were first cast and later forged, and show how large cannons terrorized civilians and soldiers in WWI and WWII. Moving to the present, we feature the 40-ton self-propelled Crusader that launches 100-pound steel artillery shells more than 33 miles.