Stealth Technology (Civ6)/Civilopedia

The ability to creep around unseen and unleash havoc is the fantasy of every five-year-old; modern scientists are close to making it reality. Modern stealth technology is a combination of multiple military projects and experimental science expanded beyond what humans can see, trying to both hide and detect objects by radar, acoustics, thermal readings, or other less readily visible methods. Low observable technology, as stealth tech is also known, has been utilized since ancient hunters wrapped themselves in vegetation and/or skins to sneak up on animals. In the wake of the Napoleonic Wars, when all those bright red and blue uniforms made soldiers wonderful targets, various European nations began to experiment with camouflage.
During the First World War, the Germans tested the use of cellulose acetate as a covering for their airplanes, a transparent fabric that they hoped would make the craft harder to spot. The Canadians and British likewise experimented with “diffused lighting camouflage” during the next world war, but it was rendered obsolete by advances in radar. However, the German U-480, covered with anechoic rubber tiles to absorb the waves of active sonar, was the world's first true stealth submarine. The Germans also were developing the Horten Ho 229 fighter-bomber, with carbon powder in the glue to absorb radar waves and other tricks to make it “invisible.”
The Horten never flew, but in 1958 AD the American Central Intelligence Agency requested funds to design a stealth recon aircraft to replace the U-2 spy planes. The United States Air Force initiated its own research project in 1960, developing special screens for the air intakes, radar-absorbent materials and paint. In 1964, Lockheed's Skunk Works produced the SR-71 “Blackbird.” A high-altitude stealth aircraft with – along with the above – canted vertical stabilizers and composite materials, lowering its radar signature significantly. It was followed in the 1970s by the stealth F-117 fighter and B-2 bomber. No doubt there are newer stealth aircraft, and even ships and ground vehicles, but those are as yet unseen by the public (or anyone else, if the technology works).