During World War II, it was crucial for Allied troops to maintain secrecy in their radio and telephone transmissions. To that end, messages were encoded, but the ongoing concern was that Japanese (and German) code breakers could break the codes and thereby know the disposition, movement, and intentions of Allied troops. In 1942, the United States hit on a solution for more effectively conducting the war in the Pacific by keeping codes secret: it recruited Navajo as “code talkers.” These soldiers, including the two shown in this photograph (Henry Bake and George Kirk), were members of the U.S. Marine Corps. They used their language to encode messages in battlefield transmissions. Navaho was chosen because of the complexity of the language, because it was largely unwritten, and because even other Native Americans could not understand it. The Japanese were never able to break the code.