John Fremont's expeditions of 1842 and 1843-44 were the most spectacular reconnaissances of the American West since Lewis and Clark. Performed under the auspices of the Army Bureau of Topographical Engineers, the expedition's published reports and maps brought a factor of dependability and trustworthiness that would aid American settlement of the West. Fremont's reports provided a chronicle of heroic adventure which inspired western emigration, as well as capturing national attention.

Although the great "pathfinder" would merely follow the established route of the Oregon Trail, his reconnaissance of the Great Salt Lake and his ability to articulate the concept of the Great Basin provided important geographical information about a region that was largely unknown. Fremont's published reports and Charles Preuss' maps became widely used by western travelers and were even quoted by emigrants in their journals.

With the exception of his route taken over the Blue Mountains, Fremont followed the 1843 route of the Oregon Trail from Fort Boise to The Dalles. But at The Dalles, having completed his primary orders to connect his reconnaissance with the surveys of naval Commander Charles Wilkes, Fremont disregarded orders to return to the United States by way of the Oregon Trail. Instead, he explored south from The Dalles along the eastern side of the Cascade Range. This expedition across central and southern Oregon and into the Great Basin and Sierra passes was his most significant contribution to western exploration.

Historical Context
John Charles Fremont was born in 1813 in Savannah, Georgia, and educated at the College of Charleston, South Carolina. In 1838, he was commissioned a second lieutenant in the Army Bureau of Topographical Engineers and accompanied Joseph N. Nicollet's expeditions surveying and mapping regions of the upper Mississippi and Missouri Rivers in 1838-39. While working with Nicollet, Fremont learned to conduct scientific field work and record observations.

After this apprenticeship, Fremont was given command of his own expedition, a quick survey of the Des Moines River which he carried out in the late summer of 1841. When he returned Fremont married Jessie Benton, daughter of the powerful and influential Senator Thomas Hart Benton of Missouri and the foremost advocate of westward expansion. Already a follower of Benton's politics, Fremont was now assured of Benton's continued support, allowing him great freedom for his explorations and which would ultimately make him a hero in the cause of Manifest Destiny. Under Benton's influence a small appropriation was made for the Topographical Engineers to dispatch a scientific expedition along the Oregon Trail to the Rocky Mountains; the reconnaissance would be led by his son-in-law Fremont.

Fremont left Washington on May 2, 1842. By the 22nd, he was in St. Louis. Charles Preuss, a German cartographer and scientist, traveled with Fremont and would accompany him on three expeditions, providing scientific validation for Fremont's published findings. Also along was a veteran of the Rocky Mountain fur trade, Kit Carson, whom Fremont had met on the steamboat heading up the Missouri. Hired as the expedition's guide, Carson would later become famous through Fremont's writings.

At Chouteau's Landing, Fremont spent twenty days carefully equipping his party, mostly French voyageurs, and started out on June 10 following the route of the Oregon Trail along the Platte River. Being several days behind Elijah White's emigrant caravan, the trail was easy to follow with its many discarded items showing the way. Fremont's expedition followed the regular trail to Fort Laramie, up the Sweetwater, past Independence Rock and Devil's Gate, and reached South Pass on August 8. Fremont then turned north to investigate the Wind River Mountains and picking what appeared to be the loftiest peak, Fremont and four men climbed to the top. On the summit, Fremont raised a special American flag with thirteen stripes and a field bearing an eagle surrounded by two banks of stars. It was a romantic act which coupled with his romantic writings captured the imagination of a young nation. The mountain was named Fremont's Peak.

Fremont then returned to Missouri and with the assistance of his wife Jessie, Fremont wrote his official report as quickly as possible and submitted it to the Senate on March 2, 1843. One thousand copies were ordered printed. The scientific value of the report was limited, but the impression made upon the public mind conveyed an emotion and ideal of heroism.

In early spring, 1843, Colonel J. J. Abert, head of the Topographical Bureau, received a letter from Senator Benton containing suggestions for an expanded survey into the west. Subsequent orders drawn up by Colonel Abert directed Fremont "to connect the reconnaissance of 1842 with the surveys of Commander Wilkes on the coast of the Pacific Ocean, so as to give a connected survey of the interior of the continent." In 1841-42 naval Commander Charles Wilkes had made a reconnaissance in Oregon as far as Fort Nez Perces and had sent the Emmons-Eld party south into California (by approximately the later Applegate Trail). From these surveys, a reliable map of the Northwest was compiled. The plans of the Topographical Bureau and of Benton now called for Fremont to link his expeditions with those of Wilkes and return from Oregon by way of the Oregon Trail.

The 1843-44 expedition started out with 39 men and included French voyageurs, mountain men, and a few green hands, including Jacob Dodson, a young Black servant of the Benton household. The guide was legendary mountain man Tom "Broken Hand" Fitzpatrick. Charles Preuss was along to collect specimens, help with the astronomical observations, maintain scientific instruments, and make topographical sketches of the landscape. Preuss and Fremont were the only scientifically trained men on the expedition, which carried a very limited number of scientific instruments. Included in the equipment was a howitzer, the presence of which on a scientific expedition was an outrage to Abert and a burden for the party to carry; and although Fremont considered it useful, it was fired only a few times, including once upon a herd of buffalo.

More than a thousand emigrants used the Oregon Trail in 1843's Great Migration. Demand for supplies around the jumping off point at Westport made it hard to outfit an expedition. When Fremont got started he was behind the emigration and would follow it all the way to Oregon. The expedition followed the Oregon Trail for a time but turned south to explore the Kansas River. Later the party split into two divisions, Fitzpatrick with the main group of twelve wagons turned northward to the Oregon Trail on the Platte River while Fremont and fifteen men went straight ahead for a survey. The divisions met at Fort St. Vrains, where Fitzpatrick again took the main force to the Sweetwater route of the Oregon Trail while Fremont ventured south to the Arkansas River, where Kit Carson joined the party. After abandoning the search for a new route through the mountains up Cache de la Poudre River, Fremont turned north to the Sweetwater and crossed the mountains via South Pass.

Fremont followed the Oregon Trail to Green River and Bear River. There he turned south to explore the Great Salt Lake, one of the primary objectives of the expedition. On September 6, after weeks of groping down the valley of the Bear River and across miles of marshy land, they were able to see "the object of our anxious search -- the waters of the inland sea, stretching in still and solitary grandeur far beyond the limits of our vision." Fremont used an inflatable rubber boat for a marine reconnaissance, collected plants and rock specimens, and made astronomical observations to fix its exact location on future maps. But perhaps most important were Fremont's general evaluations of the country around the lake and in the vicinity of the Bear and Weber rivers, for it was Fremont's report with its glowing descriptions that persuaded Brigham Young that the Great Salt Lake was the place for his people to settle.

At Fort Hall, the Hudson's Bay Company post on the Oregon Trail, Fremont's expedition was reunited for the first time since Fort St. Vrain. The wave of emigrants ahead of Fremont had left the fort short of supplies, but Fremont intended to press on. When Fremont offered to pay off those who wished to return home, eleven men turned back. From Fort Hall, the expedition followed the Snake River to Fort Boise across a landscape that Fremont characterized as a "melancholy and strange-looking country -- one of fracture and violence and fire."

Fremont arrived at Fort Boise (HBC) on October 9. From there, with the exception of his route over the Blue Mountains, Fremont followed the 1843 route of the Oregon Trail from Fort Boise to The Dalles. Trailing about two weeks behind the emigrants, Fremont crossed the Snake River at Fort Boise, went through Keeney Pass, crossed the Malheur River and passed Tub Mountain to Farewell Bend (where in his later report he articulated his concept of the Great Basin for first time). From there, he went up the Burnt River Canyon, over the divide to Powder River, and on to the Grande Ronde Valley.

At the crossing of the Grande Ronde River (north of La Grande), Fremont "determined to leave the emigrant trail in the expectation of finding a more direct and better road across the Blue mountains." The expedition continued on a northern course across the valley following an Indian trail and encamped on Willow Creek near Imbler. The next day their course took them to Indian Valley (Elgin) where they left the valley and ascended Gordon Creek to the summit. Fremont's route continued through the vicinity of Tollgate, along the ridge of Lincton Mountain (where Mount Hood was observed at a distance of 180 miles), then descended to the Walla Walla River. Whitman's mission was reached the next day, October 24.

When Fremont moved on to the Hudson's Bay Post of Fort Nez Perces, his official orders to "connect with the surveys of Commander Wilkes" were now met; Fremont had reached the Columbia River. For emigrants to Oregon, Fremont considered this point to be the end of the overland journey estimating the distance east to Westport on the Missouri River as 2,000 miles of "necessary land travel in crossing from the United States to the Pacific ocean on this line." At the time of their arrival, Fremont observed the emigrant party led by Jessie Applegate and their nearly completed boats. He also noted that "the other portion of the emigration had preferred to complete their journey by land along the banks of the Columbia, taking their stock and wagons with them."

On October 28, Fremont resumed his expedition down the south bank of the Columbia (Upper Columbia River Route) toiling through deep loose sands and over fragments of volcanic rock -- a sharp contrast to the rapid progress of Applegate's fleet of boats that glided by. Fremont arrived at The Dalles on November 4, just after the last of the emigrants had departed. There he learned of the tragic wrecking of one of the boats and the drownings of Applegate's twelve year old son, a nephew, and a family friend.

Camping near the Methodist mission at The Dalles, Fremont declared the termination of his overland journey. Writing to Fitzpatrick, who was still at Fort Nez Perces, Fremont directed him to abandon the expedition's carts, make pack saddles, and reunite the party at The Dalles from which point they would commence a homeward journey. Kit Carson was placed in charge of camp at The Dalles, Fremont, with Preuss, Bernier, and Dodson, went on by canoe to Fort Vancouver.

Upon reaching Fort Vancouver, Fremont was hospitably received by Dr. John McLoughlin, the Chief Factor of the Hudson's Bay post. In just two days Fremont was supplied with the provisions needed to refit and support his expedition for a winter journey to return to the states. Fremont chose not to complete his transcontinental journey with a trip to the Pacific Ocean. Citing the conditions of the rainy season and having fulfilled his mission of connecting with the Wilkes' surveys, he felt he could not justify delaying his return home while waiting for favorable weather. On November 10, in a Mackinaw boat and three canoes manned by Canadian voyageurs and Indians, Fremont started back up the Columbia to return to The Dalles.

After a difficult passage through wind and rain, Fremont arrived again at The Dalles on November 18. The camp was now occupied in making the necessary preparations for a homeward journey. Provisions gained from Fort Vancouver consisted of a three month supply of flour, peas, and tallow. Purchased form the mission were some California cattle which were to be driven on the hoof. Other livestock consisted of 104 mules and horses which would have to rely on what grass could be found as they traveled.

Fremont announced that the expedition would not be returning home via the Oregon Trail, as directed by his orders, but would instead take a new route, a great circuit to the south and southeast to explore the Great Basin region. In taking this new route, Fremont wished to ascertain the character or existence of three landmarks: an examination of the Klamath Lake area, which he believed formed a table land between the headwaters of the Deschutes and Sacramento rivers; a search for the mythical Buenaventura River, which was said to flow westward from the Rocky Mountains to the Pacific; and a survey of the Rockies near the headwaters of the Arkansas and Colorado rivers. The wisdom of mounting such an expedition at the onset of winter must have been questioned, but Fremont claimed his men welcomed the challenge. In his report Fremont wrote

It was a serious enterprise, at the commencement of winter, to undertake the traverse of such a region, and with a party consisting only of twenty-five persons, and they of many nations -- American, French, German, Canadian, Indian, and colored -- and most of them young, several being under twenty-one years of age. All knew that a strange country was to be explored, and dangers and hardships to be encountered; but no one blanched at the prospect. On the contrary, courage and confidence animated the whole party. Cheerfulness, readiness, subordination, prompt obedience, characterized all; nor did any extremity of peril and privation, to which we were afterwards exposed, ever belie, or derogate from, the fine spirit of this brave and generous commencement.

Thus late in 1843, having followed the Great Migration of pioneers across the Oregon Trail to Oregon, Fremont would now make what would be his most significant contribution to western exploration: a reconnaissance south from The Dalles along the eastern side of the Cascade Range, over the Sierra Nevada, and back across the Great Basin. The Oregon portion of this expedition lasted form November 25 through December 26.

New exploration in the Oregon Country
November 25. The expedition started their journey south from The Dalles. The little wagon which had carried Preuss and the scientific instruments was left behind at the mission, but the howitzer was taken along. They started about noon and camped at Fifteen Mile Creek (probably near Dufur).

November 26. Views of Mount Adams, Mount Saint Helens, and Mount Hood were noted. Following the right fork of the Indian trail they reached Tygh Ridge, overlooking the Tygh Valley, and descended and camped at either Tygh Creek or White River opposite an Indian village.

November 27. Two Indian chiefs who had accompanied Fremont from The Dalles, Stiletsi and White Crane, took their leave. The expedition then ascended the Tygh Prairie crossing Juniper Flat. Near the vicinity of Wapinitia, Fremont observed a small trail taking off toward a low point in the Cascades where he surmised there could be a pass to the Willamette Valley. An early camp was made on Nena Creek.

November 28. The party traversed broken, high country, partly timbered, and crossed a ridge (probably in the vicinity between Simnasho and the Mutton Mountains). To the west, they could see a high plain extending about ten miles to the foot of the mountains (likely Schoolie Flat and Mill Creek Flat). That evening, camp was made in a basin narrowly surrounded by rocky hills.

November 29. They emerged from the basin by a narrow pass upon the Warm Springs River and descending the stream came upon hot springs (Kahneeta) situated on both sides of the river. Fremont commented that those on the east side were formed into deep handsome basins, which would have been delightful baths and measured their temperature at 89 degrees. Those on the other side of the river measured 134 degrees. Crossing the river, they ascended to a high plain and obtained a view of six peaks (Mount Jefferson, Three Fingered Jack, Mount Washington, and the Three Sisters) affirming the chained system that constitutes the Cascade range. The trail paralleled the chasm of the Deschutes River until camp was made on a small stream.

November 30. Continuing along the high plain, the expedition arrived suddenly on the verge of a steep and rocky descent into a drainage running directly across their path from the mountains on the west (the Metolius River, now Lake Billy Chinook). Here Fremont remarked upon chasm-like valleys and vertical precipices which rendered the region impracticable for wagons and which could barely be entered by horses. At such places the howitzer had to be disassembled and separately descended by hand. When they reached the bottom, the expedition continued west a few miles and camped where Fremont collected samples of geologic strata that were later declared to be some of the most remarkable deposits of fossilized Protozoa on record.

December 1. From camp they forded the ice lined Metolius River, where the water was 3-4 feet deep and a hundred feet wide. One of the guides pointed out several salmon traps in the water, one of them about twelve feet in diameter. A steep ascent was made on the opposite side and camp was made on a height of land in a marshy place among the pines where there was an abundance of grass (probably Fly Creek). Here they met a Nez Perce family who had in their herd one particularly fine horse which Fremont sought in trade for a good cow. The wife wanted the cow, but the man loved the horse too much to part with it.

December 2. Travel continued over a stony elevated plain scattered with cedar and pine. As they gained elevation, the snow and ice increased. Camp was made on another large tributary of the Deschutes River (probably Squaw Creek).

December 3. The party traveled up Fremont Canyon and camped on a hillside covered with snow that they used for water because they were unable to reach any stream (probably near Sisters).

December 4. On leaving their camp, they followed a mountain trail, passing over a plain (similar to the course taken by Highway 20) until descending into a valley of another branch to the Deschutes where they found occasional meadows of good grass (probably Tumalo Creek and Shevlin Park).

December 5. The country was all pine forest and the weather too warm for winter clothes. After a few hours ride, they came upon the Deschutes River which they ascended along the west bank. Fremont remarked that in all their journeying, they had never traveled through a country so abounding in falls and that at every place they came near the river they heard the roaring of falls (perhaps Dillon Falls and Benham Falls). An early encampment was made on what had been an Indian camp. A great number of deer horns lay about and leaning against one of the trees was a handsome new set of lodge poles. Fremont noted had the owners been here, he would have purchased them, but as they were not, he left the expedition's own worn out poles in their place along with a small quantity of tobacco.

December 6. They continued up the stream and met a village of Nez Perces with a fine band of horses who appeared to be coming down from the mountains. Also with them were a few Snake Indians (possibly slaves). From the forest, the expedition emerged into an open valley where the river (Deschutes) was very broad and issued from a great mountain ridge to the west. Here they crossed and continued up the southern and smaller branch (Little Deschutes) over a level country consisting of alternating meadows and forest.

December 7. Travel was easy following the stream and Fremont appreciated the great beauty of the country.

December 8. The expedition crossed the Little Deschutes (probably near the confluence of Crescent Creek) and followed the trail leading through the pine forests a little east of south.

December 9. Pleasant weather continued as they followed the trail through pine forests descending very gently towards the south.

December 10. Coming upon an extensive meadow, or lake of grass, surrounded by timbered mountains, Fremont believed they had reached Klamath Lake. (Actually, they had reached Klamath Marsh, some thirty miles north of the lake.) Fremont found it to be a picturesque and beautiful spot rendered even more attractive by the abundant and excellent grass which the expedition's animals badly needed. An encampment was made on the point of land that makes a narrow neck connecting the western and eastern shores of the marsh (Military Crossing Road). Wary of the Klamath Indians and seeing smoke from Indian fires around the marsh, Fremont ordered the howitzer to be fired. The smokes in the distance immediately disappeared.

December 11. Fremont determined to pay a visit to the Indian village in the middle of the marsh. Following their guides who had already made contact, Fremont's party were met by the chief and his wife and escorted into the village. There they found huts grouped together on the bank of the river. The huts were large and round, perhaps 20 feet in diameter, with rounded tops where the door was located to descend into the interior; within, they were supported by posts and beams. Great quantities of small fish, smoked and dried, were suspended on strings about the lodge. Heaps of straw lay about from which their shoes were made, as well as hats, and parti-colored mats about four feet square which Fremont purchased to lay under blankets and use for table cloths. Fremont found that the language spoken by these people was different from the Shoshone and Columbia tribes; this caused communication to be conducted only by sign language, leaving Fremont unable to obtain certain information about the country that lay ahead. The guides who had conducted the expedition thus far were about to return to The Dalles. Fremont tried to persuade the Klamaths to accompany him further, but they refused.

December 12. Fremont's camp was thronged with Indians, but being mindful of the disaster that had befallen Jedediah Smith, the camp was kept on constant guard. According to the best information Fremont had been able to obtain, after a few days' travel east, he would reach another large lake. Breaking camp in a snow storm, the expedition crossed the marsh (at Military Crossing Road) and reaching the east side, turned up into a cove where they found a sheltered place among the timber and encamped (probably Skellock Draw).

December 13. The expedition continued up the hollow and entered an open pine forest on the mountain. Snow was four to twelve inches deep and the howitzer was hard to move. Unexpectedly, the Klamath chief and a few others came to help pilot for a day or two. After traveling east for several hours, they reached a considerable stream (Williamson River) and camped.

December 14. Traveling for seven hours through a thick snow storm, the expedition came upon the headwaters of another stream that issued from the mountain in an easterly direction before turning southward. Drawing a picture on the ground, the guides indicated that this stream continued a great distance, uniting with many other streams becoming a great river. Fremont deduced that this water formed the principle stream of the Sacramento River, the main affluent of San Francisco Bay, and that its headwaters were north of 42 degrees latitude and within the United States. (Actually, this was a tributary of the Sycan River which flows into the Klamath River.)

December 15. Fremont made gifts to the Klamaths who had guided them this far and before turning back, the chief pointed out a course north by east that would lead Fremont to the lake where no more snow would be found. Fremont then crossed his Sacramento River and traveled across a hard-frozen swamp (Sycan Marsh) and into a pine forest gradually ascending a mountain.

December 16. They traveled through snow three feet deep, climbing the mountain's gradual slopes. Towards noon the forest looked clear ahead and riding to the spot (Fremont Point) they found themselves "on the verge of a vertical and rocky wall of the mountain. At our feet -- more than a thousand feet below -- we looked into a green prairie country, in which a beautiful lake, some twenty miles in length, was spread along the foot of the mountains, its shores bordered with green grass." Fremont named these two places Winter Ridge and Summer Lake. Looking across the landscape before him, Fremont realized that he stood upon the western rim of the same Great Interior Basin that he had entered four months earlier to explore the Great Salt Lake. Turning north and following the rocky wall for four or five miles, the expedition finally succeeded in getting down an extremely difficult descent. Night had closed in before they reached the bottom and those who arrived first built bright fires to guide the others.

December 17. The howitzer, which was left halfway up the mountain, was retrieved in the morning and the party enjoyed the summer-like temperatures as they recovered themselves and reorganized.

December 18. Fremont followed a clear Indian trail along the narrow strip of land between the western shore of the lake and the high rocky wall they had looked down two days before. Knowing that they were in a country where water and grass would be scarce, Fremont camped near the southeastern point of the lake.

December 19. After a two hour ride in an easterly direction, the expedition reached the Chewaucan River, a rapid stream flowing out of the mountains, and following it downstream, they entered the Chewaucan Marsh covered with high reeds and rushes. Here they found large patches of ground that had been turned up by Indians digging for roots. Crossing the marsh towards the eastern hills and passing over a bordering plain of heavy sands and sagebrush, they camped along the Chewaucan River where they could see ahead a high, dark-looking ridge.

December 20. Following the Chewaucan River downstream, the expedition came upon another large lake, which, along its eastern shore, was closely bordered by the high basaltic cliffs which walled it in. Fremont named it Lake Abert in honor of his commanding officer, Colonel John J. Abert, Chief of the Army Bureau of Topographical Engineers. The escarpment along the lake's east side is now called Abert Rim. Following an Indian trail which led along the base of the precipice, Fremont went north along the lake shore. The lake's water was fetid and saline -- unsuitable for drinking -- and so the group continued until late in the evening hoping to find a spring emerging from the hillside. Finding none, they halted to make a dry camp and built brush fires to guide those who were struggling along behind.

December 21. After two hours of travel, they reached a place where the mountains made a bay leaving a low bottom at the north end of the lake. Here they found numerous hillocks covered with rushes in the midst of which were deep holes, or springs of pure water, and covering the bottom was abundant grass for their livestock. Camp was made for the remainder of the day while Fremont rode ahead to view their position and sketch of the lake and its basin. Ascending the bordering mountain, Fremont observed flocks of ducks on the lake, numerous tracks of Indians, and acres of recently burned grass.

December 22. Leaving the lake, the expedition curved their course to the southeast in order to avoid the rocky ridges they could see to the east (perhaps Poker Jim Ridge). Crossing an extensive sage plain, they could see in the distance ahead a range of snowy mountains (probably Mt. Warner and Hart Mountain) and the country gradually declining towards the foot of them. Riding on until dark, they made camp among the sage bushes on the open plain. Two India-rubber bags filled with water that morning afforded water for camp, and rain during the night formed pools for the animals. Where they camped, Indians had made circular enclosures, about four feet high and twelve feet across, made of sage brush.

December 23. Riding towards the mountain, Fremont found a lake at its foot (perhaps Anderson Lake). Passing around its southern end, they ascended the slope at the foot of the ridge and found several springs and good grass.

December 24. Seeing another lake to the south (probably Hart Lake), Fremont followed a broad trail along the ridge and camped at the far end where they had good grass and pure water.

December 25. On Christmas morning, Fremont was roused by the men firing small arms and the howitzer in a salute to the day. Given the occasion, Fremont bestowed the name Christmas Lake on the place (today's Hart Lake) and wrote "always, on days of religious or national commemoration, our voyageurs expect some unusual allowance; and, having nothing else I gave each of them a little brandy, (which was carefully guarded, as one of the most useful articles a traveler can carry,) with some coffee and sugar, which here, were sufficient luxuries to make them a feast." Resuming their journey south, they crossed to a similar basin (Crump Lake) which was walled in on the west by a lofty mountain ridge (Fish Creek Rim). Fremont noted, "The plainly beaten trail still continued, and occasionally we passed camping grounds of the Indians, which indicated to me that we were on one of the great thoroughfares of the county." In the afternoon, they attempted to travel east, but were turned back by the impassable country and encamped on the valley bottom.

December 26. Fremont continued south and camped on a creek on the right side of the valley (perhaps Coleman Valley). Taking a navigational reading of the stars, Fremont determined that their camp was directly on the forty-second parallel (today's Oregon - Nevada border).

Into California and homeward bound
Fremont continued south hoping to find the fabled Buenaventura River, but my mid-January the expedition was foundering and Fremont, rejecting an alternative of spending the winter at Pyramid Lake, determined to turn westward and cross the Sierra Nevadas into California. Snowstorms lashed the party and local Indians advised against such an attempt through the deep snows, but by February 20 they reached the summit of Carson Pass, 9338 feet high. By March 5, they were on the valley floor of the Sacramento River recovering at Sutter's Fort.

On March 24, Fremont's recuperated and resupplied expedition headed south through the San Joaquin Valley and then southeast through the Tehachapi Pass and on to the Old Spanish Trail. While crossing the southern end of the Great Basin, large bands of Utah Indians began to menace the party and the men became aware that they had lost the traces of the trail. It was then the expedition guide began to lead them out of Utah and across the Rocky Mountains to reach Bent's Fort on July 1. By August 6, Fremont was back in St. Louis, the acclaimed leader of the most spectacular official reconnaissance of the American West since Lewis and Clark.

With his wife Jessie again helping him, Fremont presented his 600 page report to Congress on March 1, 1845. As had his previous work, the report combined Fremont's breathless narrative with scientific information, maps, sketches, and practical advice for travelers and settlers. The Senate order 10,000 copies, combined with his first report, printed for sale as A Report of the Exploring Expedition to the Rocky Mountains in the Year 1842, and to Oregon and North California in the Years 1843-44. All of them were quickly purchased by an adoring public; several publishing houses in the United States and Europe brought out their own versions. The following year, Preuss completed his detailed seven-part map of the Oregon Trail from Westport to Walla Walla, which became, with Fremont's report, a standard guide for emigrants. These publications proved to be a boon to American settlement of the West.

Reference Source http://www.oregonhistorictrailsfund.org/trails/index.php

Bibliography
Scholarly documents
Beckham, Stephen Dow. "In Their Own Words: Diaries and Reminiscences of the Oregon Trail in Oregon," Vol. 1, a report prepared for the Oregon Trail Coordinating Council, 1991.
Evans, John W. Powerful Rockey: The Blue Mountains and the Oregon Trail, 1811-1883. LaGrande, OR: Eastern Oregon State College, 1990.
Fremont, John C. Topographical Map of the Road from Missouri to Oregon. Compiled by Charles Preuss. Published in seven sections; Government Printing Office, Washington DC, 1846.
Goetzmann, William H. Army Exploration in the American West, 1803-1863. New Haven: Yale University Press, 1959.
Gudde, Erwin G. and Elisabeth K., eds. Exploring with Fremont: The Private Diaries of Charles Preuss. Norman: University of Oklahoma Press, 1958.
Harris, Edward D. John Charles Fremont and the Great Western Reconnaissance. New York: Chelsea House Publishers, 1990.
Jackson, Donald and Mary Lee Spence. The Expeditions of John Charles Fremont. Vol. 1. Chicago: University of Illinois Press, 1970.
Mattes, Merrill J. The Great Platte River Road. Lincoln: University of Nebraska Press, 1969.
McArthur, Lewis A. Oregon Geographic Names. Sixth Edition. Portland, OR: Oregon Historical Society Press, 1992.
Meinig, D. W. The Great Columbia Plain: A Historical Geography, 1805-1910. Seattle: University of Washington Press, 1968.
Nielsen, Lawrence E. In the Ruts of the Wagon Wheels: Pioneer Roads of Eastern Oregon. Bend, OR: Maverick Publications, 1987.
Shane, Ralph M. "Early Explorations Through Warm Springs Reservation Area," Oregon Historical Quarterly, Vol. 51 (1950).
Stern, Theodore. "The Klamath Indians and the Treaty of 1864," Oregon Historical Quarterly, Vol. 57 (1956).
Stern, Theodore. The Klamath Tribe: A People and Their Reservation. Seattle: University of Washington Press, 1966.

​John Fremont