The Second World War was a period of unprecedented technological progress that saw the invention of powerful new weapons by both sides. Some of these weapons were highly ingenious, such as the bouncing bomb developed by the British inventor Barnes Wallis, which was employed on the famous "dambuster" raids against Germany. Even more significant, however, were the weapons that went on to change the shape of 20th century warfare: rockets, missiles and the atom bomb.

Rockets

Solid-fuel rockets had been used in warfare before WWII, but it was only during the course of the war that rocket-based weapons were developed to the point where they bestowed a significant tactical advantage. Widely fielded examples included the German Nebelwerfer ground-based multiple rocket launcher, which entered service in 1942, and the British RP-3 air-to-ground rockets that were fitted to numerous aircraft types in the latter years of the war. Probably the most iconic solid-fueled rocket of the war was the bazooka: a shoulder-launched, man-portable weapon that was used by the U.S. Army from 1942 onward.

Long-Range Missiles

While all the major powers fielded short-range rockets, only Germany put serious effort into the development of long-range, liquid-fueled rockets. The result was the V-2, a 14-ton, vertically launched missile with a range of 200 miles and a top speed of 3,500 miles per hour. The V-2 was one of two long-range weapons deployed by the Germans, the other being the V-1 flying bomb. Both the V-1 and the V-2 were launched in the thousands, mainly against London and Antwerp in Belgium. The V-1 was the ancestor of today's cruise missiles, while the V-2 was the world's first ballistic missile.

Guided Weapons

Another innovative concept that emerged during WWII was in-flight guidance onto a moving target. One of the earliest examples was the Fritz X anti-ship bomb, first deployed by the German Air Force in 1943: An operator on the launch aircraft guided the bomb to its target using radio control. Around the same time the U.S. Navy deployed an even more sophisticated anti-ship bomb called the Bat, which used radar to home isolate the target without needing a human operator. Another anti-ship homing weapon was the Zaunkoenig torpedo, fitted to German U-boats from 1943 onward, which used underwater sound waves rather than radar to locate the target.

The Atom Bomb

The most notorious weapon of WWII was the atom bomb, which utilized the recently discovered process of nuclear fission to produce hitherto undreamed-of explosive power. The U.S. Army's top secret Manhattan Project developed two bomb designs, both of which were used against Japan in 1945. A "Little Boy" uranium bomb leveled the city of Hiroshima on Aug. 6, while a "Fat Man" plutonium bomb was dropped on Nagasaki three days later. Both bombs had a power equivalent to tens of thousands of tons of conventional high explosive. The bombings led to the Japanese surrender, but they also triggered the nuclear Arms Race that dominated the Cold War years.