[3] Francesco Lanzoni has pointed out that the list of bishops that leads back to Marcian of Tortona is a compilation of the 16th century and that its contents are highly suspect.

[5] The Bishop of Tortona, Vincenzo Capelli, nonetheless organized an event in October 1875 to celebrate the 18th centenary of Martianus' episcopal consecration.

[7] The first bishop, according to Fedele Savio, was St. Innocentius, who in his opinion was the immediate predecessor of St. Exuperantius (381), the first of whom we have certain historical record, and who was highly praised in a sermon of Maximus of Turin (or of Ambrose of Milan).

In 877, Pope John VIII, fearful of the continued Saracen raids on the west coast of Italy, begged for assistance from the Emperor Charles the Bald.

[9] In the 1120s, Bishop Peter caused considerable trouble by illegally and uncanonically taking control of five parishes belonging to the diocese of Bobbio.

[11] Another Bishop Pietro was one of those who in 1241 were made prisoners by Emperor Frederick II at the Battle of Giglio, while on their way to attend a council in Rome called by Pope Gregory IX.

[13] Bishop Melchior Busetto (1255–1284) was responsible for building the Hospitale San Michele, as well as the parish church of Sant'Andrea, which collapsed in ruins in 1622.

Uberto Gambara[15] (1528–1548) was a papal diplomat, who began his career as Nuncio to Portugal, and then, in 1527 to Henry VIII of England, from whom he was to beg military assistance against the Emperor Charles V. He returned to Rome without success, and carrying the request of Cardinal Wolsey to be granted plenipotentiary powers to settle the divorce of Henry VIII and Catherine of Aragon.

When Clement VII was imprisoned in the Castel S. Angelo by the forces of Charles V, Gambara was sent to France to beg assistance from King Francis I in obtaining the Pope's release.

He was named papal Governor of Bologna after the sack of Rome, and continued to serve in that office after being appointed Bishop of Tortona by Pope Clement VII.

During his years as Bishop of Tortona, he participated in the Coronation of Charles V as Emperor in Bologna in 1532, and was absent as papal legate or nuncio in Germany (1532).

The plight of Tortona was made greater due to the firm support of Bishop Oberto for the legitimate Pope Alexander III rather than the Emperor's antipope Victor IV.

[24] The Chapter of the Cathedral was composed of five dignities (the Archdeacon, the Provost, the Primicerius, the Archpriest, and the Dean) and eighteen Canons (one of whom was the Theologus, another the Penitentiary).

[36] In spring 1799, Pope Pius VI, who had been driven from Rome and compelled to live at Siena and then in the Certosa near Florence, was under arrest and being conducted by the troops of the French Directory to imprisonment in France.

The Austrian army in the Po Valley was advancing toward Piacenza, and the French were anxious to avoid the capture of their hostages.

[39] The Jesuits had previously been suppressed, by Pope Clement XIV on August 16, 1773, through the Bull Dominus ac Redemptor Noster.

[45] Bishop Carlo Francesco Carnevale (1818–1831) ordered the restoration of the Collegiate Churches of Broni, Casèi, Castelnuovo, Viguzzolo, and Voghera.

[48] Two religious orders, the Capuchins and the Clerci Regulari Ministeri Infirmaribus (Camillians), were reestablished in the diocese following the departure of the French.