Sunday 29th. Capt. Bartleson with C. Hopper started to explore the route to the head of Mary’s river, expecting to be absent 8 or 9 days — the Company to await here his return.

All that the Bidwell-Bartleson Party knew about this region was that they had to find Mary’s River. They had been told by Captain Fitzpatrick that Mary’s River, what we now call the Humboldt River, was the only way to cross the Great Basin to the mountains. If the whole group were to go wandering around looking for it, the exploration might be fatal, so they sent off two men on a scouting trip, and the rest stayed where they had water and grass for their animals.

The first non-native explorer to trace and name the river was the Canadian fur trapper Peter Skene Ogden. He had named it Mary’s River after his Native American wife. John C. Fremont was the one who decided to name it after the famous German naturalist Alexander von Humboldt.

John Bartleson had taken the position of captain of the expedition. When he and his friends joined the company he insisted on being made captain, probably feeling that as an older and more experienced man, he was more qualified to lead the group. John Bidwell did not get on well with him. He wrote:

He was not the best man for the position, but we were given to understand that if he was not elected captain, he would not go; and he had seven or eight men with him, and we did not want the party diminished.

Like Bartleson, Charles Hopper was an older man, being about forty at the time. He was an experienced hunter and trapper, and no doubt an asset to the company. He returned East with the Chiles party in 1842, gathered up his family, and returned to California in 1847. He settled on a farm near Napa and lived there until his death in 1880.