The Choctaw Codetalkers. Image created before 1918.
As World War I drew to a close, the United States had a continuing problem of phone calls being intercepted by German forces. One could be fairly certain that a German spy would hear any telephone call made. Unfortunately, voice-scrambling technology wouldn’t be invented for decades. The United States came up with several inventive solutions to the problem, but unfortunately none of them worked for any length of time.
First, the Army tried trench codes. They worked for a time, but after they had been in use for a while, the Germans readily cracked them. Another solution, sending messengers between camps, failed because Germans captured about one in four.
So, what was the Army to do? One smart commander, Captain Lewis, realized that the languages used by American Indians are extremely complex and difficult to learn. He capitalized on the complexity as a code, employing eight Choctaw Indians during the Mousse-Argonne campaign, which turned out as the final German push of the war.
The Indians:
Simply put, the Indians were stationed at command posts, and spoke all important telephone calls in their native language, translating from and into English for their commanders. German intelligence wasn’t able to figure out what the new American code was or to even think about breaking it.
Within 24 hours of the United States starting to use Choctow Indians language as a form of encryption, the tides of war changed in favor of the United States. Within 72 hours, the Germans were in retreat.
The Choctow weren’t used again in an unclassified military effort (other data may still be classified). However, the Navajo tribe was utilized in World War II, where they had equal effectiveness at stumping German cryptographers.