The Code That Couldn’t Be Broken

The U.S. was at a huge disadvantage when it entered World War II in December 1941. The Pearl Harbor attack had crippled the Navy’s fleet of ships in the Pacific Ocean. By the spring of 1942, the powerful Japanese military controlled much of the Pacific, threatening Australia, an American ally, and drawing ever closer to the U.S. itself.

For the U.S. and its allies, winning the Pacific would be a massive operation. Communication was among the biggest challenges. Relaying battle plans and controlling troop movements over thousands of miles of ocean required Marines to talk by radio—and in code so that the enemy couldn’t understand. But the Japanese were highly skilled at deciphering codes. It seemed that they could anticipate the Americans’ every move. 

The U.S. faced huge problems when it entered World War II in December 1941. The Pearl Harbor attack had badly damaged the Navy’s fleet of ships in the Pacific Ocean. By the spring of 1942, the powerful Japanese military controlled much of the Pacific. It was threatening Australia, an American ally. And it was moving closer to the U.S. itself.

For the U.S. and its allies, winning the Pacific would be a huge job. Communication was one of the biggest challenges. To send battle plans and control troop movements over thousands of miles of ocean, Marines had to talk by radio. They did that in code so the enemy could not understand. But the Japanese were expert at deciphering codes. They seemed to predict the Americans’ every move.

In Los Angeles, California, a man named Philip Johnston thought of a solution. The son of Christian missionaries who worked with the Navajo, Johnston had grown up on the tribe’s reservation, a huge 27,000-square-mile area in New Mexico, Arizona, and Utah. He knew how complex the Navajo language was. Because there was no widely used written version, almost no non-natives could understand it. Johnston contacted Marine officers with the idea of developing a code based on Navajo. 

In Los Angeles, California, a man named Philip Johnston thought of a solution. He was the son of Christian missionaries who had worked with the Navajo. He had grown up on the tribe’s reservation, a huge 27,000-square-mile area in New Mexico, Arizona, and Utah. Johnston knew how complex the Navajo language was. There was no written version, and few non-natives could understand it. Johnston contacted Marine officers with the idea of developing a code based on Navajo.

To most Navajos, that idea would have seemed highly ironic. For years beginning in the 1860s, the U.S. government had forced Navajo children to attend boarding schools designed to replace their native ways—and language—with more “American” ones. Even after they didn’t have to, many Navajo parents sent their kids to those schools because they were better than the ones on the reservation. 

Now Navajos were being asked to use their once-forbidden language to help protect the U.S. In early 1942, the Marines started a project at Camp Pendleton near San Diego, California, with 29 young men. The Navajos were first given 211 common terms used in battle. For each, they devised a code word with a unique Navajo spin (see “Code of Battle,” below). For example, they called fighter planes, which were smaller and lighter than bombers, hummingbirds. 

On top of this, the coders expanded their word list by spelling out English words and place names with a code based on Navajo words. For example, they would replace the English letter A with the Navajo for ant: wol-la-chee. In all, their vocabulary would number more than 800 terms. 

The Navajos memorized the entire list, allowing them to be incredibly fast in transmitting messages. In field tests, they could send a four-line message in 20 seconds. (A standard coding machine took 30 minutes.) Best of all, no one other than the code talkers—not even other Navajos—could understand the messages. 

Military officials were impressed. But would the code work on the battlefield?

To most Navajos, that idea would have seemed odd and unexpected. Beginning in the 1860s, the U.S. government had spent years forcing Navajo children to attend boarding schools. Those schools were designed to replace their native ways and language with more “American” ones. Later, many Navajo parents chose to send their kids to those schools because they were better than the schools on the reservation.

Now Navajos were being asked to use their once-forbidden language to help protect the U.S. In early 1942, the Marines started a project at Camp Pendleton near San Diego, California. Twenty-nine young Navajo men took part. They were given 211 common terms used in battle. For each, they created a code word with a unique Navajo spin. (See “Code of Battle,” below.) For example, they called fighter planes hummingbirds. That was because fighter planes were smaller and lighter than bombers.

Next, the coders increased their word list. They spelled out English words and place names using a code based on Navajo words. For example, they would replace the English letter A with the Navajo for ant: wol-la-chee. In all, their vocabulary would number more than 800 terms.

The Navajos memorized the entire list. That made them incredibly fast in sending messages. In field tests, they could send a four-line message in 20 seconds. (A standard coding machine took 30 minutes.) Best of all, no one except the code talkers could understand the messages—not even other Navajos.

Military officials were impressed. But would the code work on the battlefield?

They soon found out. In July 1942, the Japanese invaded Guadalcanal in the Solomon Islands, giving them an air base even closer to Australia. Alarmed, U.S. military officials organized a hurried invasion of the island. On August 7, the first wave of Marines stormed the beach in what would be a six-month ordeal. In November, the code talkers joined them.

The fighting was brutal. Marines trudged through thick jungle, facing death at every step. Because of the jungle tree line, U.S. planes couldn’t see where to bomb Japanese positions or drop supplies. The code talkers and their radios were often the only lifeline the Marines had to medicine, ammunition, food, and each other. 

Chester Nez, one of the original 29 code talkers, later wrote about working nonstop for 24 hours at a time, crammed into a foxhole. He described his first radio transmission, calling in an attack on a Japanese machine gun that had his patrol pinned down. 

“A runner approached, handing me a message written in English. [I transmitted the message to another code talker:] ‘Enemy machine gun nest on your right flank. Destroy.’ Suddenly, just after my message was received, the Japanese gun exploded, destroyed by U.S. artillery.” 

Working so quickly with a code the enemy couldn’t crack made the Navajos a valuable new weapon. By the time the Japanese finally withdrew from Guadalcanal in February 1943, the code talkers had proved themselves.

They soon found out. In July 1942, the Japanese invaded Guadalcanal in the Solomon Islands. That gave them an air base even closer to Australia. That worried U.S. military officials, who organized a hurried invasion of the island. On August 7, the first wave of Marines stormed the beach. It would be a six-month struggle. In November, the code talkers joined them.

The fighting was brutal. Marines trudged through thick jungle. They faced death at every step. Dense jungle tree lines made it hard for U.S. pilots to see where to drop bombs on the enemy or supplies for U.S. troops. The code talkers and their radios were often the only lifeline the Marines had to medicine, ammunition, food, and each other.

Chester Nez was one of the original 29 code talkers. In later years, he wrote about working nonstop for 24 hours at a time, crammed into a foxhole. He described his first radio transmission, when he called in an attack on a Japanese machine gun that had his patrol pinned down.

“A runner approached, handing me a message written in English. [I sent the message to another code talker.] ‘Enemy machine gun nest on your right flank. Destroy.’ Suddenly, just after my message was received, the Japanese gun exploded, destroyed by U.S. artillery.”

Working so quickly with a code the enemy could not crack made the Navajos a powerful new weapon. The Japanese finally retreated from Guadalcanal in February 1943. By then, the code talkers had proved themselves.

But the fighting was far from over. The war in the Pacific became a relentless series of battles over strategic islands, leading up to a possible U.S. invasion of Japan. Sam Sandoval went through training in 1942 and soon was “in the thick of it,” as he would say. He would see action at Guadalcanal, Bougainville, Peleliu, Guam, and Okinawa—some of the most fearsome battles of the war.

In each engagement, the code talkers were crucial. One of the bloodiest fights was over the island of Iwo Jima, beginning in February 1945. In the month it took the Marines to take the island, the battle claimed the lives of some 6,800 Americans and 22,000 Japanese. 

“The entire operation was directed by Navajo code,” Signal Officer Major Howard Connor later said. “They sent and received over 800 messages without an error. Were it not for the Navajo code talkers, the Marines would never have taken Iwo Jima.”

But the fighting was far from over. The war in the Pacific became a harsh series of battles to control islands that could lead to a possible U.S. invasion of Japan. Sam Sandoval went through training in 1942. Soon he was “in the thick of it,” as he would say. He would see action at Guadalcanal, Bougainville, Peleliu, Guam, and Okinawa. Those were some of the most terrifying battles of the war.

In each battle, the code talkers were essential. One of the bloodiest fights was over the island of Iwo Jima. It began in February 1945. It took the Marines a month to take the island. The battle claimed the lives of some 6,800 Americans and 22,000 Japanese.

“The entire operation was directed by Navajo code,” Signal Officer Major Howard Connor later said. “They sent and received over 800 messages without an error. Were it not for the Navajo code talkers, the Marines would never have taken Iwo Jima.”

The war dragged on until August 1945, when the U.S. dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki. Sandoval still remembers the greatest message he ever decoded, on August 14: “The Imperial forces of Japan have surrendered.”

Soon the code talkers would begin coming home, but not to the post-war economic boom that the rest of the U.S. enjoyed. Instead, the Navajos headed back to their reservation, where jobs and opportunity were scarce.

To make matters worse, the code talkers couldn’t reveal what they had done. The U.S. government had declared their operation top secret.  The Navajo code wasn’t declassified until 1968. 

The war dragged on until August 1945. It ended when the U.S. dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki. Sandoval still remembers the greatest message he ever decoded, on August 14: “The Imperial forces of Japan have surrendered.”

Soon the code talkers would begin coming home. But they did not benefit from the post-war economic boom like the rest of the U.S. Instead, the Navajos headed back to their reservation. There, jobs and opportunity were scarce.

To make matters worse, the code talkers could not talk about what they had done. The U.S. government had declared their operation top secret. The Navajo code was kept secret until 1968.

Today, more than 75 years after their first mission in 1942, the Navajos are recognized as national heroes. In a White House ceremony held by President Donald Trump to honor them last November, 90-year-old code talker Peter MacDonald said that their act of patriotism crossed all boundaries of language and culture. “What we did,” he said, “truly represents who we are as Americans.”  

Sandoval is also proud of his service to the country, of being a Navajo, and of his unique part in using a military code that was never cracked by the enemy.

“Many have tried throughout the world to break that code,” he says. “No one can.”

Today, more than 75 years after their first mission in 1942, the Navajos are recognized as national heroes. Last November, President Donald Trump honored them in a ceremony at the White House. Code talker Peter MacDonald is now 90 years old. He said that their act of patriotism crossed all boundaries of language and culture. “What we did,” he said, “truly represents who we are as Americans.”

Sandoval is also proud of his service to the country, of being a Navajo, and of his unique part in using a military code that was never cracked by the enemy.

“Many have tried throughout the world to break that code,” he says. “No one can.”