Padre Fermín de Francisco Lasuén de Arasqueta was born at Vitoria-Gasteiz, Spain, on 7th June, 1736. He joined the Franciscan order and was ordained in 1752. Lasuén volunteered to become a missionary and arrived in Mexico in 1761 and seven years later he was sent to Baja California.
Lasuén was involved with Junipero Serra in establishing the Mission San Diego de Alcalá on Presidio Hill in honour of Saint Didacus. Serra wrote about his motivation for the Franciscans establishing these missions: "Above all, let those who are to come here as missionaries not imagine that they are coming for any other purpose but to endure hardships for the love of God and the salvation of souls, for in far-off places such as these, where there is no way for the old missions to help the new ones because of the great distance between them, the presence of pagans, and the lack of communication by sea, it will be necessary in the beginning to suffer many real privations."
Lasuén was based in San Diego. The settlement was close to a Kumeyaay village. Tracy Salcedo-Chouree, the author of California's Missions and Presidios (2005), has pointed out that their "natural suspicion flowered into animosity when the soldiers began raping their women and stealing their food." On 15th August, the colonists came under attack. One of the Spanish settlers was killed during the raid. Junipero Serra recorded what happened: "He entered into my little hut with so much blood streaming from his temples and mouth that shortly after I gave him absolution... he passed away at my feet, bathed in his blood. And it was just a short time after he died before me that the little hut where I lived became a sea of blood. All during this time, the exchange of shots from the firearms and arrows continued. Only four men of our group fired while more than twenty of theirs shot arrows. I continued to stay with the departed one, thinking over the imminent probability of following him myself, yet, I kept begging God to give victory to our Holy Catholic faith without the loss of a single soul."
The battle for San Diego, the first in the Spanish settlement of California, changed the relationship between the settlers and the Kumeyaay. They now became more peaceful and began revisiting the camp, bringing along their wounded, probably hoping that Spanish remedies would prove as powerful as Spanish arms. Don Pedro Prat, who had received some medical training, did what he could do to help the wounded men brought to the settlement.
On 28th April, 1769, after two days of strenuous travel, Junipero Serra arrived at Mission San Borja, where he was greeted by Fermin Francisco de Lasuén. Serra wrote: "My special affection for this excellent missionary detained me here for the next two days which for me were very delightful by reason of his amiable conversation and manners." Although it was in an isolated spot with a shortage of water, Lasuen had managed to convert several hundred Indian families living in the area.
In 1774 the missionaries based in San Diego moved about six miles inland from the Presidio to take advantage of more productive farmland and a better source of water. Lasuén and Luis Jayme, a priest from Sant Joan, Majorca, organised the building of the Mission San Diego de Alcala. It is claimed that they converted more than 500 local people to Christianity. He also helped establish the Mission San Juan Capistrano in 1776 before moving on to San Luis Obispo, a mission between San Francisco and Los Angeles.
Fermin Francisco de Lasuen, later recalled: "A missionary priest has to engage in many duties, many of which only concern him as a means to something else. He is responsible for the spiritual and temporal welfare of people who are many and varied. He has individuals who are more dependent on him than small children, for there are many needs that arise...and many different things to be done for the different groups that make up the community. He is surrounded by pagans, and placed in charge of neophytes who can be trusted but a little."
Junipero Serra died on 28th August, 1784, at the age of 70, at Mission San Carlos Borromeo. Fermin Francisco de Lasuén became the new President of the Californian missions. Francis F. Guest wrote: "Junipero Serra and Fermin Francisco de Lasuen, in many respects, were opposites. Both were highly intelligent, yet Lasuen, gifted with a degree of perceptiveness to which Serra could not lay claim, easily surpassed him in human relations. Serra was more learned in theology, in which he had a doctors degree; but Lasuen, though lacking the erudition of the first Father President, was endowed with greater psychological insight. Both excelled as administrators, vet, here too, Lasuen revealed a flexibility, a subtlety, a suppleness which Serra did not manifest."
Fermin Francisco de Lasuén died on 26th June, 1803.