Gallery: The Twentieth Century's Best-Kept Military Secrets

During World War II, we wrote, "It is a safe bet that every major military power is experimenting with rocket devices, although all of them regard the work as highly secret." We speculated that German reports of "secret [rocket] weapons" were mere propaganda, while Britain had developed a mysterious mechanism that could release ten rockets in mid-air. Unfortunately, we were mistaken: in 1944, Germany launched a number of V-2 rockets over Paris, Antwerp, and London, among other targets. The Allies' rocket weaponry program depended largely on the Soviets' Katsyusha rocket launchers (similar to the one pictured left), which were less expensive than the V-2s, but which were also troublesome to reload. After the war, the United States recruited several German engineers for another hush-hush program, Operation Paperclip, which asked former Nazi scientists to adapt V-2 technology for use by the United States.

Read the full story in "Secret Rocket Weapons Blast Tanks and Planes"