The Mexican government issued the Santa Ysabel grant in 1844 to two men who represented very different paths into California's landowning class. José Joaquín Ortega was from a Mexican ranching family with deep roots in Alta California — a representative of the Californio elite who held land grants as part of the colonial social order. Ortega was connected to that order through family as well: he had married a sister of Pío Pico, who would become the last Mexican governor of California. Edward Stokes arrived through a completely different route — an English sailor who had worked his way from Hawaii to California and found a place within Californio society through business relationships and eventually the land grant system. The 17,719-acre rancho brought them together as co-grantees of some of the most productive mountain grazing land in the region.

Stokes's life in California before the Mexican-American War represents one of the many paths by which foreigners entered the Californio world. Some converted to Catholicism, married into prominent families, and became naturalized Mexican citizens — the formal requirements for holding land grants. Others operated in the gaps of enforcement that frontier California made possible. What is certain is that Stokes was present at the Battle of San Pasqual on December 6, 1846, one of the bloodiest engagements of the Mexican-American War in California. The battle, fought in the valley to the west of the rancho, pitted US Army forces under General Stephen Kearny against Californio lancers. Stokes did not survive. His death left his interest in the rancho to be resolved through the legal and financial proceedings that followed the American takeover.

After the Mexican-American War and California's admission to statehood, the United States Land Commission began reviewing the extensive system of Mexican land grants that covered much of California. The process was lengthy, expensive, and often ruinous for original grantees who could not afford the legal fees or who lost their cases to technical objections. The Santa Ysabel rancho received its American patent in 1872 — nearly three decades after the original grant and more than two decades after the war that changed California's political status. By that point, the ownership history had become complex, with various interests in the land having changed hands through sales, inheritance, and legal proceedings. The 1872 patent marked the moment when the rancho's Mexican legal identity was formally converted into an American property title.

The Santa Ysabel valley and the surrounding mountain terrain that the rancho occupied remained in agricultural use after the land grant era ended. The valley's combination of elevation, water access, and good soils made it valuable for cattle ranching — the same purposes the original grantees intended. Today the area around Santa Ysabel includes the town of that name, the Santa Ysabel mission asistencia, and the lands of the Iipay Nation of Santa Ysabel, whose connection to this landscape predates the Spanish, Mexican, and American periods by millennia. The rancho grant, like most of California's land grant system, was an episode in a much longer human history of the mountains east of San Diego.