The ability to wage battle at night is a great tactical advantage, but devices that let soldiers see well in the dark were not invented until the 1940s. Fighters illuminated land and sea battles with searchlights and flares at the beginning of the twentieth century, and star-shell artillery was used in the two world wars to cast light where it was needed. Then during World War II, both the Germans and the Allies developed more sophisticated night vision devices. This early night vision equipment consisted of an infrared filter placed over a searchlight. The observer looked through a binocular-like or telescope-like viewer that translated the infrared emissions into an electron flux displayed on a luminescent screen. Both the Germans and the Allies fitted their tanks with these viewers. But because both sides had infrared viewers, they could spot each otherÕs searchlights. Even after...