In 1847, while Commodore Robert F. Stockton and Colonel John C. Fremont were engaged in winning California from the Mexicans, Fremont gave $3,000 to Thomas O. Larkin, American consul at Monterey, with which to purchase a tract of land overlooking San Francisco Bay.

Just as Fremont and Stockton were completing their conquest, there appeared on the scene, General Stephen Kearney, who claimed supreme authority from the Government in Washington to complete the conquest and establish a civil government.

Commodore Stockton, ignoring Kearney, commissioned Fremont as Governor, and a conflict as to who had supreme authority ensued. Fremont refused to recognize that a General had authority over a Commodore, so he remained loyal to Commodore Stockton, with whom he had previously co-operated so successfully, with the apparent sanction of the Government in Washington.

A few months later, Kearney’s authority being confirmed, he ordered Fremont to accompany him East, where he was court-martialed and found guilty of disobedience and conduct prejudicial to military discipline. He was sentenced to dismissal. President Polk, refusing to approve the findings, except on technical grounds, remitted the penalty, and desired Fremont to continue in the service. Fremont, however, unwilling to concede that he had done anything wrong, resigned.

Senator Benton, Fremont’s father-in-law, claimed that the verdict was a deliberate attempt to ruin Fremont by the West Point element, as Fremont was not a West Pointer and had become too popular. The people, generally throughout the Nation, considered that he had been unjustly treated.

Just before leaving California, for the humiliating court-martial, Fremont learned that Larkin, using his own judgment, had purchased with the $3,000 a tract of 44,000 acres in what is now Mariposa County.

In October, 1848, he set out for California, with two objects in view; first to find passes for a railroad from the Atlantic to the Pacific; and second, to get back his $3,000, with which he intended to settle down in California and study law.

Led astray by a guide, and after losing his entire outfit and a number of his men and enduring extreme hardships, he turned southward across the Rio Grande into Mexico. Later, continuing his course westward, he encountered, along the Gila River, a caravan of more than a thousand Mexican men, women, and children, with their wagons, mules, and horses, going westward. Asking the reason, he was told, “Gold has been discovered in upper California”.

The news of the discovery of gold in California had traveled to Mexico by steamer quicker than it had traveled overland. Fremont’s thoughts immediately reverted to the 44,000 acres which he owned in California, but which he had never seen. Perhaps, there was gold on his own land. Acting with characteristic quickness, he engaged twenty-eight Mexicans to work for him on his Mariposa estate.

His plans had been changed, and his $3,000 investment was to become a controlling influence on his career, enabling him to become a national, and even a world figure. This was surely a contrast to the humiliating court-martial and the herculean hardships, which he had just passed through. So, with the magic words, “Gold has been discovered in upper California,” ringing in his ears, John C. Fremont came, in the early part of 1849, to Mariposa.

After placing his Mexican miners, whom he brought with him and grubstaked, on some of the creeks on the property he expected to get, Fremont then endeavored to locate the boundaries of his estate.

His deed called for a grant of land, known as Las Mariposas, to the extent of ten square leagues, lying within the boundaries of the Sierra Nevada (commonly known as Snow) mountains and the rivers known by the name of Chauchilas, Merced, and San Joaquin, as granted in 1844 by Micheltorena, then Governor of California, to Juan B. Alvarado, who had conveyed it to Fremont. It was a floating grant, with its exact boundaries undetermined, at the time of making, and Fremont thought that he would be entitled to his choice.

Some of his Mexican miners called his attention to the similarity of the quartz formation in the vicinity of Mariposa to the “Veta Madre” or Mother Lode quartz gold belt in Mexico. With the aid of a surveyor by the name of Von Schmidt, he ran the lines of his survey from Mariposa Creek in a northwesterly direction to the Merced River, taking in what afterwards became generally known as the Mother Lode gold belt. It was not, for many months later, generally known, and then it took several years to prove, that gold lay in paying quantities in quartz veins in California. Fremont was the first man to prove it. His survey, being in the shape of a frying pan, for a long time, was called the “Frying Pan Claim”.

Fremont realized that it would be necessary for him to secure financial assistance, in order to work his quartz veins. He, therefore, formed a partnership, to work part of his estate, with Palmer, Cook & Co., a very prominent banking firm in San Francisco, who were also very influential in politics.

The first steam quartz mill to be erected in the State, including a small steam engine, was brought to Mariposa, in 1849, by James Duff, who although part negro, claimed that he was the first white man to settle on Mariposa Creek. The mill was put up on Mariposa Creek, near the lower end of the present town, in the month of August, 1849, and was operated by Palmer, Cook & Co., for Fremont, and was known as the Palmer, Cook & Co. mill. It had four stamps, which were lifted by the long iron cams, shaped like the letter “S”, passing through a slot in the center of each stem. It was of inferior construction and ran only for two or three years, but its results proved that gold in quartz form would produce infinitely more treasure than that contained in the hitherto seemingly vast placers, which would soon become exhausted.

The first provisional State legislature met at San Jose, December 20, 1849, and John C. Fremont was elected U. S. Senator, for the short term. He left soon afterwards for Washington, where he was very influential in securing the admission of California, into the Federal Union, as a free State.