John Marsh (June 5, 1799 – September 24, 1856), later known in Spanish as Don Juan Marsh, was a physician, ranchero, and linguist in California when it was still part of the Republic of Mexico. Born in Massachusetts, Marsh immigrated to California in 1836, where he became a Mexican citizen. He was baptized as Roman Catholic in order to buy land, and acquired the vast land grant of Rancho Los Méganos in Contra Costa. He became one of the wealthiest ranchers in California, and was among the highly influential men who worked to gain United States statehood after Mexico ceded this area following its defeat in the Mexican-American War.
Marsh knew Hebrew, Latin and Greek, and, while working as a US Indian agent at Fort Snelling, was the first person to compile a dictionary of the Siouan language. He is the namesake of Marsh Creek and Marsh Creek State Park in Contra Costa County. The John Marsh Historic Trust was organized to protect his legacy.
Early life
Born in Danvers, Massachusetts in 1799, Marsh graduated from the private Phillips Academy in Andover in 1819. He attended Harvard College from 1819 to 1823 and received a bachelor's degree. Colbruno writes that Marsh was dismissed from Harvard for participating in a student uprising. He was readmitted in 1821, after promising not to engage in any further disturbances. He originally planned to study for the ministry, but changed his major to medicine after his readmission. He studied medicine with a Boston doctor.
Marsh migrated west, living in the Michigan Territory, where he opened a school, the first in what is now Minnesota. Marsh was appointed by the federal government as a United States Indian agent for the Sioux Agency at Fort Snelling, At Fort Snelling, Marsh took a Lakota/French mistress named Marguerite Decouteaux; they had a son Charles together. Territorial Governor Lewis Cass appointed Marsh as Justice of the Peace in Crawford County (which included what is now southern Wisconsin, northern Illinois, and portions of Iowa and Minnesota), whereupon he became known as "Judge Marsh."
While at Fort Snelling, Marsh resumed his study of medicine, with the post doctor, Dr. Purcell. Because Purcell died before Marsh completed his studies, he never received a certificate. Marsh lived for a time in Prairie du Chien, Wisconsin, where he got involved in the Black Hawk War between the United States and a group of Sauk, Meskwaki (Fox), and Kickapoo, known as the "British Band". As the Sioux supported the US against their old rivals, Marsh was blamed for a Sioux massacre of Fox and Sauk warriors.
As a result, he fled the area, taking Decouteaux and their son with him and settling in New Salem, Illinois. Leaving the pair there, he returned to Prairie du Chien. Decouteaux was pregnant again and pining for Marsh,; she tried to walk the several hundred miles to rejoin him. The journey exhausted her, and she and their second child died in childbirth. Marsh placed his young son, Charles, to be raised with a family named Painter in New Salem.
He again became involved in Indian affairs. He was discovered selling guns illegally to some of the Indians and had to flee the territory, this time settling in Independence, Missouri, where he became a merchant. Marsh visited his son again before his business failed, and in 1836 he emigrated, as an employee of the American Fur Company, to Santa Fe, New Mexico. He proceeded to Southern California via the Santa Fe Trail. Both areas were part of the Republic of Mexico, which had gained independence from Spain in 1821.
Life in California
In southern California, Marsh claimed he was the only person who had any knowledge of Western (or European-style) medicine. He presented his Harvard degree to the local Mexican government of Alta California. The degree was written in Latin, which none of the local authorities could read. They took his word and granted him permission to practice medicine. Marsh was quite successful in his new profession, but his prices were very high. He sometimes charged as much as a head of cattle to deliver a baby. He is credited as being the first person to practice medicine in California.
He was often paid in the currency of the day: cowhides and tallow. Marsh joked that his adobe looked more like a warehouse than the offices of a physician. In 1836, he sold his accumulated inventory to a Boston trader for $500 and rode to Northern California seeking a ranch to purchase. Since Mexico allowed only Catholics to own land in California, he became baptized as a Roman Catholic.