In which branch of the U.S. military did most Navajo Code Talkers serve?

Most Navajo Code Talkers served in the United States Marine Corps primarily because the Marines recognized the potential of the Navajo language for secure and efficient communication during World War II. The concept of utilizing Native American languages was introduced to the Marines due to their need for an unbreakable code that was both fast and reliable. The Navajo language, with its complex structure and unique oral tradition, was ideal for this purpose.

The decision to recruit Navajos onto the Marine Corps was also influenced by several factors, including the military's deep need for secure communication methods in a time of war, particularly in the Pacific Theater, where traditional means were proving inadequate against the enemy. The Marines established a dedicated unit of Navajo Code Talkers, who developed and utilized a code based on their language that enemy forces could not decipher.

In contrast, while the Navy, Army, and Air Force utilized various forms of communication and codes, the significant and historical role of the Navajo Code Talkers is most prominently associated with the Marine Corps, where their contributions had a direct impact on several battles and campaigns.