U.S. soldiers today face enormous challenges, often stationed in desolate locations behind enemy lines. Keeping them protected is priority number one.

From the LAPD's sharp shooters to Army snipers, discover what it means to be armed and accurate.

From "safe" bullets that stop hijackers but leave aircraft unscathed to bullets that chain-saw through steel and "smart" bullets computer-programmed to hit a target, this explosive hour examines the evolution of bullets from origin in the 10:30:000s--stones and round lead balls shot from iron and bamboo tubes. Lead balls ruled until 1841 when a conical-shaped bullet changed ammo forever. We learn how to construct a modern cartridge, and at pistol and rifle ranges view demonstrations of modern firepower.

In this fiery hour, we profile five of man's deadliest weapons, focusing on the inventors, battles, and dark technology behind their lethality. We begin with the deadliest bomb ever created, the Tsar Bomba--a 50-megaton nuclear bomb with a yield thousands of times greater than the one dropped on Hiroshima. During WWI, technological advances in weaponry led to the deaths of over 8-million, and one of the deadliest killers was the machine gun. In WWII, the use of incendiary bombs killed hundreds of thousands of people. Another deadly invention of WWII was the proximity fuse, or VT fuse, that allowed artillery to detonate within a predetermined range of an enemy target. Finally, we examine VX nerve gas, thought by many to be the deadliest chemical agent ever created and suspected to have been used by Saddam Hussein with devastating results. We'll visit Edgewood Chemical BioCenter, which plays a large role in protection and detection for our troops in Iraq.

Modern arsenals have become much more sophisticated than bullets and bombs. Discover microwave-like rays that make the enemy flee when they feel the heat and laser weapons, mounted on trucks and airplanes that can blow missiles out of the sky.

Barbarians and technology, maybe they're not such a contradiction after all. It's the bow that nearly brought down Rome, and the suspension system that revolutionized the chariot.

Blade implements have been a part of civilized man's arsenal since the Paleolithic Age, when sharp tools were chipped off of flint or obsidian. But with the discovery of metallurgy, people were able to forge stronger, more versatile blade implements. We visit an axe-throwing contest in Wisconsin for an introduction to the least subtle of the blade tools. Then we visit a swordsmith and an experienced swordfighter who work in traditional methods from ancient sources, and review the history of knives.

Modern Marvels is going big, and counting down. We take the "best of" Modern Marvels and give you the MEGA Top 10 countdown. On this edition: Amazing Weapons. They're every arsenal's best asset and every enemy's worst nightmare and we're counting them down to the most amazing weapon of all.