Mariano Guadalupe Vallejo was a prominent Californio military commander and politician in the 19th century. Born in 1807 in Monterey, California, he played a significant role in the early history of California during the Mexican-American War. Vallejo served as the commander of the northern California military and was influential in the region's governance. Vallejo was also a landowner and a key figure in the development of Sonoma and the surrounding areas. He was involved in the establishment of the Bear Flag Revolt in 1846, which aimed to assert California's independence from Mexico. Vallejo's legacy includes his contributions to California's transition from Mexican to American rule.