The origin of the ancestor of Mr. Gaspar de Osma y Tricio was the so called place Osma del Duero, in which is located Burgo de Osma. Its first bishops after the new conquest was the french monk Pedro de Vituris. In 1090 he ordered the building, in the other shore of the Ucero, in the neighborhood called El Burgo, a primitive church cathedral that was later rebuilt byt the Knight of the Duero de Osma becoming the second most important cathedral in Spain.
To this Pedro de Vituris people started to call Pedro de Osma, who was later canonized as San Pedro de Osma. His tomb is currently located in the center of the old capitular room of the Burgo Cathedral in the Burgo de Osma. The tomb is magnificent and has a multicolor part with the history of the first encounter between the lord of Osma and the bishop Pedro.

In all times, Church goods have excited the greed of the secular powers. The Church of Osma wasn’t very rich in temporal goods, nevertheless, the few things it had there, was desired by the lord in that region: a brutal knight that was more Islamic than Christian. Not satisfied with taking away stuff from the Church and the bishop, imposed also strong tributes for people. In the beginning Saint Pedro made hear him his voice with sweetness: he asked the return of the goods and no bother his faithful. The knight answered with an arrogant negative. The bishop answered, as well, outraged (with reason): he sent the guilty man the Church rays and took him away of the faithful communion. When the knight knew this, he said very angrily: “I will drink the blood of the traitor”.

The knight knew that attacking the saint in the Burgo, in the middle of his town that loved him tenderly, was too outrageous. He decided to wait for a better opportunity... and he didn’t have to wait so long. One day the knight knew that the bishop went out of town to visit his diocese, so he decided to wait for him along the path that is close to the town of San Esteban de Gormaz, so that he could kill the bishop. The saint bishop was getting close to that place and the murderer was ready to finish with the holy man’s life, when, all of a sudden, he had terrible pain and fell to the ground with convulsions. The evil had taken him. His men surrounded him screaming desperately. When the bishop heard the screaming, he saw his enemy to his feet. Without showing any emotion, the saint started to pray and took him up cured of the body and soul. Since that day, the goods of the Church had an excellent defendant in the lord of Osma.