It was approaching midnight on November 4, 1942. Chester Nez, 21, was crouched in a muddy foxhole with his buddy Roy Begay. Bullets whizzed over their heads. Explosives crashed around them. At any moment, bombs could rain down from warplanes prowling the skies.

In 1942, World War II was raging around the globe. Nez was a United States Marine, and he had just arrived on Guadalcanal, an island in the southwest Pacific Ocean. For months, the Marines had been battling the Japanese Imperial Army for control of the island. Now the once-peaceful oasis had become a place of misery and death.

Nez and Begay had seen it for themselves earlier that day. They tried not to think of what they’d witnessed as they leapt from their boat and waded ashore—of the corpses of Japanese and American men floating in the water, of the tides staining the beach red with blood.

Nez and Begay were Navajo, Native men from the Southwest. Their job on Guadalcanal was one of the military’s most closely guarded secrets. Months before, they had helped invent a secret code using Diné, their native language—a language they had once been punished for speaking.

If their code worked, they could do more than help their fellow Marines take the island. They could help win the war.

That first night on Guadalcanal, Nez huddled beside Begay. Heavy rain poured down in thick sheets, filling their foxhole nearly to their chests. Nez had never been more terrified. He tried to stay focused, though. He and Begay had a job to do.

But first, they would have to survive the night.

It was almost midnight on November 4, 1942. Chester Nez, 21, was crouched in a muddy foxhole with his buddy Roy Begay. Bullets whizzed over their heads. Explosives crashed around them. At any moment, bombs could rain down from warplanes flying above.

In 1942, World War II was raging around the globe. Nez was a United States Marine. He had just arrived on Guadalcanal, an island in the southwest Pacific Ocean. The Marines were battling the Japanese Imperial Army for control of the island. The once-peaceful oasis was now a place of misery and death.

Nez and Begay tried not to think of what they had seen earlier that day—bodies floating in the water and the beach stained red with blood—when they leapt from their boat and waded ashore.

Nez and Begay were Navajo, Native men from the Southwest. Their job on Guadalcanal was one of the military’s most closely guarded secrets. Months before, they had helped invent a secret code. It used Diné, their native language—a language they had once been punished for speaking.

If their code worked, they could help their fellow Marines take the island. They could also help win the war.

That first night on Guadalcanal, Nez huddled beside Begay. Heavy rain poured down. Their foxhole almost filled with water. Nez was terrified. But he tried to stay focused. He and Begay had a job to do.

But first, they had to survive the night.

For Chester Nez, being both Navajo and a Marine was complicated. The Navajo people had a painful history with the U.S. government. In the 1860s, the U.S. made war on the Navajo and forced them off their lands. By the time they were permitted to return home, thousands of Navajo people had died.

Around that time, the U.S. government also enacted a new policy. Officials ordered that Native children be separated from their families and educated to be “like other Americans.”

Between 1869 and the 1960s, hundreds of thousands of Native children were sent to so-called Indian boarding schools, where they were forbidden from speaking their languages and practicing their cultural traditions.

Nez was one of these children. In 1929, when he was 8, he was sent from his home in Chi Chil Tah, New Mexico, to the Fort Defiance School in Arizona.

It was not a good place for Nez. His long hair was cut off and his clothing taken from him. The school matrons treated the children coldly and disciplined them harshly. When Nez was caught speaking Diné, a matron brushed his teeth with bitter soap called Fels-Naptha. (Years later, that same soap would be given to Nez and all Marines to wash their clothes.)

Nez stayed at Fort Defiance until high school, when he was sent to another school. Though he was able to go home for short visits, Nez lost years of contact with his family. Yet he was determined to hold on to his culture and his language.

And it would be Diné, the language he was told to forget, that would one day help turn the tide in World War II.

For Chester Nez, being both Navajo and a Marine was complicated. The Navajo people had a painful history with the U.S. government. In the 1860s, the U.S. made war on the Navajo and forced them off their lands. Thousands of Navajo people died.

Around that time, the U.S. government enacted a new policy. Officials ordered Native children to be taken from their families and educated “like other Americans.”

Between 1869 and the 1960s, hundreds of thousands of Native children were sent to so-called Indian boarding schools. They were not allowed to speak their languages or practice their cultural traditions.

Nez was one of these children. In 1929, he was 8. He lived in Chi Chil Tah, New Mexico. He was sent to the Fort Defiance School in Arizona.

It was not a good place for Nez. His long hair was cut off. His clothing was taken from him. The school matrons treated the children coldly and disciplined them harshly. When Nez was caught speaking Diné, a matron brushed his teeth with a bitter soap. (Years later, that same soap would be given to Nez and all Marines to wash their clothes.)

Nez stayed at Fort Defiance until high school. Then he was sent to another school. He was able to go home for short visits. But he lost years of contact with his family. Even so, he was determined to hold on to his culture and his language.

And it would be Diné, the language he was told to forget, that would one day help the U.S. win World War II.

The U.S. entered World War II in December 1941, when Nez was in 10th grade. During the war, the U.S. would fight on two fronts: in Europe, against Germany and Italy, and in the Pacific, against Japan.

By the spring of 1942, things weren’t looking good in the Pacific. Japanese forces had seized control of much of the Pacific Ocean, bringing them closer to the U.S. mainland. On the West Coast, many Americans feared invasion.

Nez longed to join the war effort. He understood that the U.S. had once fought the Navajo. He also understood that the U.S. was now the Navajo people’s country too. He wanted to fight, as his ancestors had, to protect his homeland.

In April 1942, Nez got his chance. That month, recruiters from the Marine Corps came to the Navajo reservation, looking for Navajo men to volunteer. Nez eagerly joined up.

High school would have to wait.

The U.S. entered World War II in December 1941. Nez was in 10th grade. The U.S. fought on two fronts: in Europe, against Germany and Italy, and in the Pacific, against Japan.

By the spring of 1942, Japanese forces controlled much of the Pacific Ocean. On the West Coast, many Americans feared invasion.

Nez wanted to join the war effort. He knew that the U.S. had once fought the Navajo. He also understood that the U.S. was now the Navajo people’s country too. He wanted to fight, as his ancestors had, to protect his homeland.

In April 1942, Nez got his chance. That month, recruiters from the Marine Corps came to the Navajo reservation, looking for Navajo men to volunteer. Nez eagerly joined up.

High school would have to wait.

Hundreds of Navajo men volunteered for the Marines. In the end, 29 were selected, including Nez. Those men became known as the “Original 29.”

In May 1942, they reported to San Diego for the initial training that all military recruits go through, known as basic training.

Though grueling, it was easier for them than for many others. As Navajos, they had spent most of their lives outdoors; hauling heavy loads and walking great distances were no challenge. Having carried rifles since childhood to defend their herds of sheep and goats from predators, rifle training was like a game to them. They shot with such precision that their platoon earned one of the highest marksmanship scores of any Marine platoon in history.

After basic training, Nez and the other Navajo men were taken to a classroom. Finally, they learned the true reason they’d been recruited: to create a secret code using their language.

Immediately, the men got to work. For every letter of the English alphabet, they chose a Diné word. For A, they used the Diné word for ant, pronounced wol-la-chee. B became the Navajo word for bear, pronounced shush.

To make the code harder to break, more than one Navajo word was chosen for vowels and other frequently used letters. Thus A was also the Diné word for apple, pronounced be-la-sana. The men picked other words to refer to military terms and places. The Diné word for egg meant bomb. The word for mother meant United States.

Each day, lunch was brought to them. Each day, they were released around 4 or 5 p.m. with strict orders to tell no one what they were doing.

Over the next three months, they created and perfected the code. Night after night, they practiced, speaking coded messages to each other. The men soon became known as the “code talkers.”

Now the only thing left to do was to test the code on the battlefield.

In November 1942, Nez and the other Navajo Marines arrived on Guadalcanal to do exactly that.

Hundreds of Navajo men volunteered for the Marines. But only 29 were selected, including Nez. Those men became known as the “Original 29.”

In May 1942, they reported to San Diego for basic training. It was the initial training that all military recruits go through.

The training was grueling. But it was easier for them than for many others. As Navajos, they had spent most of their lives outdoors. Hauling heavy loads and walking great distances were no challenge. They had carried rifles since childhood to defend their herds of sheep and goats from predators. So rifle training was like a game to them. They shot with such precision that their platoon earned one of the highest marksmanship scores of any Marine platoon in history.

After basic training, Nez and the other Navajo men were taken to a classroom. Finally, they learned the true reason they’d been recruited: to create a secret code using their language.

Immediately, the men got to work. For every letter of the English alphabet, they chose a Diné word. For A, they used the Diné word for ant, pronounced wol-la-chee. B became the Navajo word for bear, pronounced shush.

To make the code harder to break, more than one Navajo word was chosen for vowels and other frequently used letters. Thus A was also the Diné word for apple, pronounced be-la-sana. The men picked other words for military terms and places. The Diné word for egg meant bomb. The word for mother meant United States.

Each day, lunch was brought to them. Each day, they were released around 4 or 5 p.m. with strict orders to tell no one what they were doing.

Over the next three months, they created the code. Night after night, they practiced speaking coded messages to each other. The men soon became known as the “code talkers.”

Now they had to test the code on the battlefield.

In November 1942, Nez and the other Navajo Marines arrived on Guadalcanal to do exactly that.

When morning dawned on Guadalcanal on November 5, Nez looked up at the sun. He took a pinch of corn pollen from the medicine bag he carried with him everywhere. Touching the pollen to his tongue and the top of his head, he prayed to each of the four directions. Begay did the same, giving thanks for having survived their first hours in battle.

The two men had hardly slept in their muddy foxhole, but the blessing helped them feel alert. They grabbed their 30-pound hand-cranked radio and moved into a new position.

Suddenly, a runner approached with a message about a nest of Japanese machine guns. The moment had come for Nez to send his first battlefield transmission.

One mistake could be deadly. The American guns might fire at the wrong location. If they missed, they could wipe out their own men.

His heart pounding, Nez picked up the receiver and began to speak: “Beh-na-ali-tsosie a-knah-as-donih ah-toh nish-na-jih-goh dah-di-kad ah-deel-tahi.”

The message was received by a pair of code talkers on an American ship offshore. They translated it into English: Enemy machine gun nest on your right flank. Destroy.

Minutes later, the ship’s guns roared to life. The Japanese machine guns exploded.

“You see that?” Nez asked.

“Sure did,” Begay replied.

The code had worked.

On the morning of November 5 on Guadalcanal, Nez looked up at the sun. He took a pinch of corn pollen from the medicine bag he carried with him everywhere. Touching the pollen to his tongue and the top of his head, he prayed to each of the four directions. Begay did the same, giving thanks for having survived their first hours in battle.

The two men had hardly slept. But the blessing helped them feel alert. They grabbed their 30-pound hand-cranked radio and moved into a new position.

Suddenly, a runner approached with a message about a nest of Japanese machine guns. The moment had come for Nez to send his first battlefield transmission.

One mistake could be deadly. The American guns might fire at the wrong location. They might wipe out their own men.

His heart pounding, Nez picked up the receiver. He began to speak: “Beh-na-ali-tsosie a-knah-as-donih ah-toh nish-na-jih-goh dah-di-kad ah-deel-tahi.”

The message was received by code talkers on an American ship offshore. They translated it into English: Enemy machine gun nest on your right flank. Destroy.

Minutes later, the ship’s guns roared to life. The Japanese machine guns exploded.

“You see that?” Nez asked.

“Sure did,” Begay replied.

The code had worked.

Within less than two days of their arrival on Guadalcanal, it was clear that the code talkers were indispensable. Before long, every crucial radio message in the Pacific was sent using the Navajo code.

Code talkers tracked enemy positions and shared ship movements and attack plans. They called for food and medical supplies. They dodged enemy fire, lugging their heavy radios through mud and rain.

By the start of the next year, thanks in large part to Nez and his fellow code talkers, the U.S. had taken control of Guadalcanal. Finally, there was hope that America and its allies could win the war.

More code talkers were trained, until their numbers exceeded 400. For the next two-and-a-half years, American forces fought for control of islands in the Pacific, pushing north toward mainland Japan. The Navajo Marines were part of taking every island.

All the while, the code was never broken. And though code talkers served in some of the most brutal and dangerous battles, only 13 died. Like Nez, they depended not just on their training but also on their cultural and spiritual traditions to help them survive.

In less than two days, it was clear that the code talkers were indispensable. Soon, every crucial radio message in the Pacific was sent using the Navajo code.

Code talkers tracked enemy positions and shared ship movements and attack plans. They called for food and medical supplies. They dodged enemy fire, lugging their heavy radios through mud and rain.

Thanks in large part to Nez and his fellow code talkers, the U.S. took control of Guadalcanal early the next year. Finally, there was hope that America and its allies could win the war.

More code talkers were trained. Their numbers exceeded 400. For the next two-and-a-half years, American forces fought for control of islands in the Pacific. They pushed north toward mainland Japan. The Navajo Marines were part of every win.

All the while, the code was never broken. Though code talkers served in some of the most dangerous battles, only 13 died. Like Nez, they relied on their cultural and spiritual traditions—not just their training—to help them survive.

In August 1945, Japan surrendered. World War II was over at last. Around the world, people began the long work of rebuilding.

Nez soon found himself back in New Mexico with his family. It was a happy reunion. Yet Nez couldn’t tell his loved ones about his role in the war. The code talkers were still under strict orders to keep it a secret.

Nez went on to finish high school, then pursued a degree in art at the University of Kansas. He married and started a family.

But though he had left war behind, war had not left him.

After he returned from the Pacific, Nez was plagued by nightmares in which ghosts of the dead Japanese soldiers he had seen—and even touched—appeared, threatening to take him with them. Contact with the dead is avoided in Navajo culture. It’s believed that everyone has both good and bad within them. When one dies, that little bit of bad may turn into a dangerous spirit.

Nez’s father arranged for a Sing, a ceremony lasting several days that involves the creation of sand paintings and ritual chanting by a medicine person known as a hataałii. The ceremony performed for Nez was an Enemy Way.

Enemy Ways were not only for people who had been to war, but also for those returning from boarding schools, to heal their spiritual and psychological wounds.

Nez’s ceremony was successful, and his bad dreams subsided.

In August 1945, Japan surrendered. World War II was over. Around the world, people began the long work of rebuilding.

Nez went back to New Mexico and his family. It was a happy reunion. Yet Nez couldn’t talk about his role in the war. The code talkers were still under strict orders to keep it a secret.

Nez finished high school, then pursued a degree in art at the University of Kansas. He married and started a family.

Though he had left war behind, war had not left him.

Nez was plagued by nightmares. In them, he saw the ghosts of the dead Japanese soldiers he had seen—and even touched. They threatened to take him with them. Contact with the dead is avoided in Navajo culture. It’s believed that everyone has both good and bad within them. When one dies, that little bit of bad may turn into a dangerous spirit.

Nez’s father arranged for a Sing, a ceremony lasting several days. It involves the creation of sand paintings and ritual chanting by a medicine person known as a hataałii. The ceremony performed for Nez was an Enemy Way.

Enemy Ways were for people who had been to war. But they were also for those returning from boarding schools, to heal their spiritual and psychological wounds.

Nez’s ceremony was successful. He stopped having bad dreams.

As for the code? In 1968, new technology made it possible to send secure messages by radio as fast as the Navajo teams had done. The code was declassified at last.

Finally, Nez and the other code talkers who’d kept their secret for 23 years could be recognized for their heroism. In 2001, Nez traveled to the White House, where he and other code talkers were awarded gold medals by President George W. Bush.

The last surviving member of the Original 29, Chester Nez passed on in 2014, at the age of 93.

Yet the shared legacy of the code talkers has continued. This legacy is about more than the pride Native people feel in the crucial work they did during the war. It’s also about the importance of language and culture.

Today, among the Navajo Nation’s 400,000 members, 170,000 people speak Diné. Across the country, Native nations are working to preserve and restore their languages, many of which have been in danger of disappearing. In many ways, it was the code talkers who helped inspire these efforts.

To this day, hundreds of their names, including Nez’s, can be seen on the bricks of a veterans memorial in Window Rock, Arizona, in the heart of the enduring Navajo Nation.

As for the code? In 1968, new technology made it possible to quickly send secure messages by radio. The code was declassified at last.

Nez and the other code talkers had kept their secret for 23 years. Finally, they could be recognized for their heroism. In 2001, Nez traveled to the White House. He and other code talkers were awarded gold medals by President George W. Bush.

Chester Nez died in 2014 at the age of 93. He was the last surviving member of the Original 29.

Yet the shared legacy of the code talkers lives on. This legacy is about more than the pride Native people feel in the crucial work they did during the war. It’s also about the importance of language and culture.

Today, 170,000 of the Navajo Nation’s 400,000 members speak Diné. Across the country, Native nations are working to preserve their languages, many of which have been in danger of disappearing. The code talkers helped inspire these efforts.

To this day, hundreds of their names, including Nez’s, can be seen on the bricks of a veterans memorial in Window Rock, Arizona, in the heart of the enduring Navajo Nation.