Rancho Guenoc was a 21,220-acre (85.9 km2) Mexican land grant in present-day Lake County, California given in 1845 by Governor Pio Pico to George Rock.
[3] George Rock by deed dated 13 Jan 1847 and witnessed by Richard Fowler and Andrew Hoppener,[4] sold Rancho Guenoc to Jacob P. Leese (1809-1892).
Leese evidently abandoned the claim, and Rancho Guenoc was taken over by Captain Archibald Alexander Ritchie and Paul S. Forbes in 1852.
[5][6] With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored.
In 1888, the British actress Lillie Langtry, purchased a 4,200 acres (17 km2) of Rancho Guenoc to raise racehorses and grapes.