[1] In 1845 under the law for secularization of former Church properties, his older brother Governor Pío Pico granted Andrés Pico and his associate Juan Manso a nine-year lease for the Mission San Fernando Rey de España lands, which encompassed nearly the entire San Fernando Valley.

Under the terms of secularization, the sale excluded the Mission compound and its immediate surroundings, which were reserved for Don Andrés.

In 1846 Pico led an attack on forces commanded by U.S. General Stephen Watts Kearny at the fierce but inconclusive Battle of San Pasqual.

In 1853, Don Andrés acquired a half interest in Rancho Ex-Mission San Fernando from Eulogio F. de Celis; it was split along present-day Roscoe Boulevard, with his brother Pio Pico's land being the southern half of the San Fernando Valley to the Santa Monica Mountains.

Vineyard was elected to the California State Senate from Los Ángeles County (Pico's old seat) four months later,[8] but would die in office.

[2] Ex-Mission San Fernando fell into ruins until the mid-20th century, when the Roman Catholic Church conserved about one fourth of the old mission quadrangle.

The site of the main mission buildings are now occupied by a parochial high school, including the old, monumental front facing east toward the former Fort Tejon Road.

The sites of the Butterfield stagecoach stables, and the outbuildings and storage buildings of Don Andrés' ranch and hacienda, have been lost under development of the modern urban community of Mission Hills.