From Code Talker: The First and Only Memoir By One of the Original Navajo Code Talkers of WWII, by Chester Nez (Dutton Caliber, 2011), Kindle Loc. ~1870:
Our messages relayed calls for ammunition, food, and medical equipment back to the supply ships waiting offshore. Messages transmitted the locations of enemy troops to U.S. artillerymen. Messages told of something unexpected that had happened in battle. Messages reported on our own troop movements. Messages forwarded casualty numbers, the Navajo code keeping the Japanese from learning of American losses in each foray. Throughout the days of battle to come, we sent those numbers back to our commanders on the ships each night.
After being in operation for just forty-eight hours, our secret language was becoming indispensable.
The hilly terrain on Guadalcanal posed real problems for the men operating mortars and artillery. Muzzle-loaded mortars were low-velocity, short-range weapons with a high trajectory, particularly well suited to uneven terrain. A mortar could drop into an enemy trench that artillery fire flew right over. Shells fired by field artillery reached a higher velocity and followed a flatter trajectory. Howitzers were similar to mortars in function, but larger.
The men firing all of these weapons dealt with a serious issue. Artillery, howitzers, and mortars targeted an enemy who was frequently nose to nose with the American soldiers at the front. Marksmen had to clear the hills and the heads of our own troops, causing them no injury, while drawing an accurate bead on the enemy. This became especially ticklish when we were “walking fire in.” That meant that our weapons were shooting behind the enemy and drawing them closer to the American troops at the front line. As they drew closer, we continued to fire behind them, moving both our fire and the Japanese troops closer and closer to our own troops. There was no room for error in a maneuver like that. The old Shackle communications system took so long to encode and decode, and it was so frequently inaccurate, that using it for the transmission of on-the-fly target coordinates was a perilous proposition. Frequently, in the midst of battle, instead of using the Shackle code, the Marines had transmitted in English. They knew the transmissions were probably being monitored by the Japanese, so they salted the messages liberally with profanity, hoping to confuse the enemy.
We code talkers changed all that.
Roy and I traveled close to the mortars. And the mortars, due to their short range, placed us well within the enemy’s line of fire. Not as close as the riflemen, who were always out front leading the attack, but still close.
Sweat streamed down my back. I transmitted coordinates detailing the locations of Japanese and American troops. I knew men’s lives depended upon the accuracy of each word. I wiped my brow with a sleeve, but never stopped talking. Out of the corner of one eye, I saw a flash of fire. Sand and shrapnel kicked up into the heavy gray sky. I kept talking.
Just then, a spotter, sent out to locate a pocket of Japanese soldiers and artillery, returned. Someone handed a slip of paper to me, bearing the exact Japanese location. The same paper also reported the location of forward U.S. troops.
I squinted, rubbed my eyes, read the paper again. Any error could cause the death of my fellow fighting men. I’d sent hundreds of messages. Messages swam in my brain, jamming and tumbling over one another. I shook my head to clear it.
I translated the data into Navajo code and spoke into the microphone that fit neatly into my fist like a baseball. I glanced in the direction my transmission would travel. Roy and I crouched so close to the American artillery and mortars that I could almost have shouted the information.
I spoke clearly, carefully. I pictured the code talker who received my message translating it back into English for the gunnery men. I imagined those men planning a trajectory, one that would fire over the heads of the Americans and hit the Japanese.
If a soldier was shot right beside us, we had been warned not to stop and help. Our transmissions could not be interrupted.