John Kinsel, Sr., one of the Navajo code talkers, has died. He was 107. Like the other code talkers, Kinsel played a decisive role in helping the Allies win World War II.

The code talkers were a group of Indigenous (also known as American Indian or Native American) soldiers who used radios to transmit classified (secret) wartime information in their Native language. Most code talkers were Navajo. With Kinsel’s death, just two code talkers are still alive. In a statement, Navajo Nation President Buu Nygren offered praise for Kinsel.

“Mr. Kinsel was a Marine who bravely and selflessly fought for all of us in the most terrifying circumstances with the greatest responsibility as a Navajo Code Talker,” Nygren said.

Born in Cove, Arizona, Kinsel was a young man in 1941, when the United States entered World War II. Within months, many Navajo men had gone to work in shipyards and other places where they could contribute to the war effort. Others decided to enlist in the military. Kinsel chose the Marine Corps.

Kinsel saw combat in numerous battles in the Pacific and received a Purple Heart after being wounded in 1945. (The Purple Heart is a military decoration for soldiers who are wounded or killed in battle.)

Kinsel also helped develop the military code that was based on the Navajo language and that the enemy found impossible to break. According to the Navajo Times, his contributions included “rabbit trail” for “route,” “turtle” for “tank,” and “bird carrier” for “aircraft.”

Olin Kieyoomia, the deputy director of the Navajo Nation Veterans Administration, said Kinsel was a hero to many.

“The Navajo Nation has lost a treasure, a hero, a man who shaped history by saving countless lives with our Navajo language and instilled pride within the Navajo Nation and the world,” Kieyoomia said in a statement. “He is an example of the title United States Marine. He will be forever missed and remembered.”