In that year Pope Clement XI, at the request of Charles Emmanuel III of Sardinia, established the Diocese of Biella by the papal bull Praecipua.

[8] In the shrine of Maria Santissima d'Oropa, situated on a mountain near Biella,[9] the diocese preserves a memorial of St. Eusebius of Vercelli, who was banished to the Orient by Emperor Constantius for his defence of Catholicism against Arianism.

St. Eusebius, according to tradition, upon his return from the East, is said to have brought three pictures of the Madonna painted on cedar wood, one of which, the image of Oropa, he placed in a small oratory he had built.

When they abandoned the place, Pope Pius II, in 1459, made over the shrine to the Chapter of the Collegiate Church of San Stefano, now the Biella Cathedral, to which it has since belonged.

In the sixteenth century, the inhabitants of Biella, in thanksgiving for their deliverance from the plague, built a church over the chapel.

One of the policies of the Franch government was the reduction in the number of dioceses both in metropolitan France and in its annexed territories.

[14] In the bull "Gravissimis Causis" of 1 June 1803, Pope Pius VII authorized the papal legate to First Consul Bonaparte, Cardinal Giovanni Battista Caprara, to suppress a number of dioceses in the ecclesiastical province of Piedmont, including Biella.

King Victor Emmanuel I of Sardinia invited Pope Pius VII to restore the good order of the Church in his kingdom, which had been disrupted by the French occupation.