Leonard John Rose was born in Bavaria, Germany in 1827. His family moved to the United States in 1839, where they lived in New Orleans, Louisiana and then moved to Waterloo, Illinois. Rose attended Shurtliff College in Alton, Illinois. He became a mercantilist, trading goods up and down the Mississippi River, and opened his own general store. Leonard John Rose married Amanda Markel Jones in Keosauqua, Van Buren County, Iowa in 1851. They would have ten children: Annie (Sanderson), Nina R. (Wachtel), Daisy (Montgomery), Maud (Easton), Mabel (Pike), Harry Ezra Rose, Leonard "Leon" John Rose Jr., Guy Rose, and Roy Rose. After a child died in the 1850s, Rose took advantage of his economic success and pursued his dream of establishing a horse breeding ranch in California. Rose sold his store and organized an emigrant train of ox driven wagons. The Rose Party, as it came to be known, set out for California from Iowa in 1858. They took the southern route to avoid Utah, passing through the territory of New Mexico instead. Native Americans assaulted their party by the Colorado River, forcing the emigrants to retreat. The Rose family spent close to two years in Santa Fe, where they bought a small inn called La Fonda.
They made their way to Los Angeles, California in 1860 and Rose bought an estate in the San Gabriel Valley. He named it Sunny Slope and it came to encompass approximately 2,000 acres. At Sunny Slope, Rose grew grapes, oranges, walnuts, and manufactured wine and brandy in the thousands of gallons a year. Rose used his economic success to pursue his interests in breeding trotter horses and racing them in harness races across the country. He bred several record setting horses and sold them individually and in a series of record breaking auctions in New York. Rose also made a large profit from selling Sunny Slope to an English company in 1887, which he used to pay off debts, buy Rose-Meade ranch, which is now part of the city of Rosemead, and build a lavish home in downtown Los Angeles. Rose began a term as a California State Senator for Los Angeles in 1887. In the following decade, he made a series of bad investments in California and Nevada that ruined him financially. In 1899, mounting financial duress drove Rose to commit suicide in his Los Angeles home. He was survived by his wife, Amanda Rosa, and eight sons and daughters. His son, Guy Rose, became an internationally renowned impressionist landscape painter.
From the description of Papers of Leonard John Rose, 1858-1953. (Huntington Library, Art Collections & Botanical Gardens). WorldCat record id: 288950411
