Truman Everts was already 54 years old, an age at which we no longer risk going on an expedition to the wilderness. The other members of the Washburn expedition were easily 15 years younger than him, including notables such as Henry Washburn, Surveyor General of Montana, or Nathaniel P. Langford, Collector General of Montana. Not to mention the armed escort, commanded by Gustavus C. Doane, Second Cavalry Lieutenant at Fort Ellis. They may be bigwigs, but they were also men in their prime, who had also served in the army during the Civil War. Everts clearly did not fit the profile of an explorer, but as an employee of the Treasury in the state of Montana, his prerogatives imposed his participation in the expedition that left Fort Ellis on August 22, 1870. Nine civilians, six soldiers, two cooks, and two porters set off on horseback up the Yellowstone River.

They spent the next few days exploring the region and naming the geographical features they encountered. Mount Washburn, of course, then logically Mount Langford and Doane. They discovered the Yellowstone Grand Canyon on August 29, and were thrilled by the beauty of the falls they reached the next day. Exploring is not as simple as it seems, and contrary to what one might think, the riders did not stay together. On the contrary, the formation was very dispersed, and they were content to remain within earshot of the other explorers, which allowed them to cover more ground. Truman Everts seemed inclined to venture alone for long periods of time. As the days passed, the group got used to this habit, and did not worry too much, especially since the old man would find the camp every evening. It was not until the evening of September 9 that the group noticed that Truman Everts had gotten lost.

Truman walked away to look for a ridge passage, and thinking he had found it, he rode into it. He was careful to shout calls to make sure he didn't separate too much from the group, but he didn't realize that the voice answering him was nothing more than the echo of his own.

So here was Truman lost in the middle of the forest and separated from his companions. He looked for a point of view to orient himself, and stopped frequently to look for traces of his friends' passing. While he was just busy examining a possible lead, his horse suddenly thought  that this guy was a little suspicious, that there was nothing good about staying with him, and that the opportunity was too good to let it pass. Truman had just enough time to see his mount disappear from the corner of his eye into the undergrowth, taking with it his food, his gun, his blanket, his matches, his fishing gear and all the rest of his belongings. All he had left was a pair of binoculars and two small knives.

The beginning of September marked the arrival of the first cold weather, and Truman's first night in autonomy was a long series of hours of darkness, cold, fear and hunger.

The following night, he thought he heard a lament and tried to discover its origin, only to discover that it came from a puma. He spent the rest of the night hanging on a tree waiting for the predator to leave.

In the days that followed, Truman definitively abandoned the idea of finding his horse and tried to get to the group's meeting point on Lake Yellowstone. He eventually reached a lake, but quickly realized that it was an undiscovered element, as was the snow-covered summit reflected in it, which would later be called Mount Everts. The area was populated by a very diverse fauna. Truman encountered pelicans, mockingbirds, swans, birds of all kinds, as well as deer, moose and Canadian sheep, unfortunately he had no way of hunting and his hunger was all the more intolerable. He therefore studied the flora, and discovered a species of thistle called "elk thistle", whose roots were edible. He therefore decided to make it the basis of his diet, and this herb was indeed to allow him to survive during the many days he would spend alone in the wild.

A little further on, he recognized the remains of a camp left by his companions. He cursed the circumstances that they didn't think to leave him provisions. However, they had left food for him, but they had concealed it so as not to attract predators, and Everts could not find it.

Fortunately, he discovered hot water pools, which offered him a refuge from the cold nights that had caused him frostbite on his feet. He spent several days between the scalding springs thinking about his chances of survival. His frostbite began to fester. And one night, while he was sleeping near a pool, he turned in his sleep, the ground collapsed and the boiling water burnt him all over his left side.

He then understood the vital need to build a fire. He reviewed the different ways of producing it, and hastily concluded that none of them were within his reach, but he finally realized that his binoculars were an excellent tool. However, sunshine was required and bad weather was settling in. Truman also decided to join civilization by passing through the Madison Mountains, far to the west.

On the way, he managed to take advantage of a few hours of sunshine to build a fire, and he got  a lot of comfort from it. However, he was woken up in the middle of the night by a huge fire started by his own campfire, and had to flee so as not to be swallowed up by the blaze.

Arriving in sight of the Madison Mountains, Everts understood the impossibility of crossing this high barrier, so he turned back towards the Yellowstone River. When he discovered a hollow tree with its bark torn off, surrounded by flattened grass, he decided to stay there for the night. But since he understood that it was a black bear's den, he took the precaution of making a fire to protect himself. As he still did not know how to secure his home, he was woken up again in the middle of the night by the forest fire that spread through his campfire, which certainly put the owner of his shelter on the run, but also burned his left hand.

For their part, the expedition members were back at Helena, after reluctantly giving up their search for Truman Everts. With a heavy heart, they put out a wanted notice for the body of their unfortunate companion. Two trappers named "Yellowstone Jack" Baronett and George A. Pritchett were planning to hunt in the area, they kept in mind the $600 reward for who could find Truman Everts' body. Several days later, as he walked along the Yellowtone River, Pritchett noticed a famished scrawny bear. He aligned it in his gunsight, then took pity on it and decided to put an end to its suffering with a hunting knife. As he approached, he understood his mistake, and asked:

"Are you Truman Everts? »

At this point, the versions of Pritchett and Everts diverge. According to Everts, the man stood up and said in a cavernous voice:

"I am the shadow of the man who once called himself Truman Everts. »

According to Pritchett, Everts rolled to the side, moaned and passed out.

In the end, Baronett walked 120 kilometres to civilization to get help, while Pritchett stayed to watch over Everts. He carried him to a cabin of miners who had come to explore the region. Everts weighed 23 kilos, suffered from frostbite on his feet and fingers, burns on his entire left side and left hand, and was unable to ingest any food. He suffered from intestinal obstruction due to his prolonged diet of roots. In the grip of unbearable pain, Everts believed he was about to die when he had just been rescued. His salvation came thanks to an old trapper who stopped at the cabin. He administered Everts a whole pint of bear fat oil, which evacuated the clot.

Everts recovered quickly thanks to Pritchett and the miners. He insisted on immediately taking the return journey, and met the group that came to assist him halfway through the road to Helena.

Pritchett and Baronett went before the judge at Helena and proudly announced that they had found Truman Everts. The judge thanked them warmly and replied that the reward was for Everts' corpse. The trappers turned around and looked lengthily at their catch. Then they left the courtroom with empty pockets.

Two years after the rescue of Truman Everts, Yellowstone National Park was created.

As for Everts, he still holds the record for the number of days spent in survival conditions in Yellowstone Park: 37.