George Smith, a former Navajo code talker who help the U.S. military during World War II by sending messages in their obscure language, has died, the president of the Navajo Nation said.

"This news has saddened me," Ben Shelly, the Navajo president, said in a post Wednesday on his Facebook page. "Our Navajo code talkers have been real life heroes to generations of Navajo people."

According to Shelly, Smith died Tuesday before the Navajo Nation’s flag was flown at half-staff until Sunday night to commemorate his life.

Using a military communications code based on the Navajo language, several hundred Navajo tribe members served as code talkers for the United States during World War II. The code talkers were instrumental in sending messages containing crucial information during key battles such as Iwo Jima.

Reports indicate that military authorities chose Navajo as a code language because it was almost impossible for a non-Navajo to learn and had no written form. It was the only code the Japanese never managed to crack.

Navajo code talkers were even forbidden from telling anyone about the code until it was publicly declassified in 1968.

According to CNN, most code talkers are now in their 80s and 90s with only a handful still alive.

"They have brought pride to our Navajo people in so many ways," Shelly said. "The nation's prayers and thoughts are with the family at this time as they mourn the passing of a great family man who served his country and protected his people."

Shelly's Facebook post didn't mention Smith's age or the cause and location of his death.