World War II and the increased usage of air power led to the rise of radar for the purpose of early warning capabilities. This was crucial due to the bombing runs conducted by Germans across Europe, specifically in Britain, as well as the pivotal role of air power in the Pacific theater. The first picture is of a captured Japanese radar set, including two indicators, two receivers, one transmitter, among other essential components. This radar was used by the Japanese Navy. The second picture shows an American Identification Unit Contactor. It was used by the Americans in Britain to identify themselves as friendly, prior to the invention of dedicated IFF (Identification Friend or Foe) transponders. There were only 500 units produced. The US Navy developed the Oscilloscope Radar, shown in picture three. It was a simplified display system which allowed a fighter pilot to utilize the radar himself, without the use of a radar operator. It was simple to use and had a range of five miles. The next two pictures show the British Airborne Intercept Radar receiver and transmitter. These were the common radar devices utilized by the British throughout World War II.