The earliest use of infrared technology in battle was during World War II (1939-45). Electric sniperscopes were mounted on top of rifles and converted infrared light of enemy soldiers into visible light, enabling the shooter to fire accurately in darkness.

Three hundred of these sniperscopes were shipped to the Pacific, but were used very little in battles against the Japanese.

These sniperscopes had some disadvantages including cumbersome batteries and low range. The USA, UK and Germany were all involved in developing infrared technology for battle. Infrared was discovered by the English astronomer, Sir William Herschel in 1800.