Before Salvatierra's modest chapel rose above the Gulf of California shore, the peninsula had swallowed every colonial ambition thrown at it. Hernan Cortes himself tried in 1535, planting a flag at what is now La Paz before retreating in the face of starvation and hostile terrain. Over the next 150 years, a parade of expeditions followed and failed. The closest anyone came was the 1683-1685 outpost at San Bruno, just 20 kilometers north, where Admiral Isidro de Atondo y Antillon and the Jesuit Eusebio Francisco Kino held on for two years before admitting defeat. That failure, paradoxically, made Loreto possible. Kino's enthusiasm for the mission field never wavered, and he spent the next decade persuading his colleagues and the authorities in New Spain to let the Jesuits try again, this time at their own expense and on their own responsibility.

The Spanish chose to build within a few hundred feet of a Monqui rancheria, a settlement of 50 to 80 people, with the area's only waterholes lying between the two communities. Tension was inevitable. Some Monqui accepted food in exchange for labor and attendance at religious services, but others grew hostile. On November 13, 1697, roughly 200 men attacked the rudimentary Spanish fortress with arrows and rocks. The Spaniards answered with a mortar and two harquebusses, and after two hours the assault ceased. Sporadic resistance continued until Easter Sunday 1698, when another violent confrontation ended Monqui opposition. Within a year, some 100 Monqui families along a 65-kilometer stretch of coast had been converted to Christianity. But European diseases were already at work. By 1733, the Monqui population at Loreto had fallen to 134. A Jesuit report from 1762 recorded only 38 baptisms over the preceding 18 years, against 309 deaths. By the time the mission closed in 1829, the Monqui as a distinct people and culture were virtually extinct.

Loreto proved, as one historian put it, "worthless as a breadbasket." There was never enough water to irrigate crops, and food had to be shipped across the stormy Gulf of California from the Mexican mainland. Periodic shortages plagued the mission for decades. Yet Loreto's geographic position made it invaluable as a base for expansion. In 1699, the need for farmland drove the Jesuits to establish a sister mission 25 kilometers inland at Biaundo. From there, new missions radiated across south-central Baja California and eventually reached the peninsula's northern and southern extremes. The stone church that still stands today was begun in 1740 and completed in 1744, a monument to persistence in a place that offered no easy rewards.

Even after the Jesuits were expelled in 1768 and replaced first by Franciscans, then Dominicans, Loreto remained the administrative headquarters of the Baja California missions. Its most consequential moment came in 1769, when Franciscan friar Junipero Serra and military commander Gaspar de Portola departed from Loreto on a joint expedition northward. That journey established missions at San Diego and Monterey and explored as far as San Francisco Bay, seeding the chain of settlements that would become modern California. The thread connecting a spring of fresh water in an inhospitable desert to the great cities of the American West runs directly through this small stone church on the Gulf shore.

Today, Loreto is a quiet coastal town in Baja California Sur, and the mission church anchors its main plaza. A museum attached to the old presidio displays colonial-era arms and religious artifacts. The bell tower, added during early 20th-century renovations, rises above a square where neighbors leave free sweaters for anyone who needs one. The building endures as the oldest standing mission in the Californias, its thick stone walls a reminder that the entire chain of Spanish settlements stretching from Loreto to San Francisco began with ten men, a wooden cross, and one Jesuit who refused to accept that Baja California could not be tamed.