[2] After the secularization of the bishopric of Passau in 1803, Gaisruck had to leave the town and served as parish priest in the Diocese of Linz till his appointment as Archbishop of Milan.

[3] The archdiocese of Milan remained vacant after the death of Cardinal Giovanni Battista Caprara in 1810 because Emperor Napoleon did not allow the appointment of a successor.

After the defeat of Napoleon in 1815, the Congress of Vienna assigned Milan to the Kingdom of Lombardy–Venetia ruled by Emperor Francis II.

On 1 March 1816 Francis II appointed the Austrian Gaisruck as Archbishop of Milan without the previous agreement of Pope Pius VII.

[5] Gaisruck was charged by some anonymous priests in front of Pope Gregory XVI of Jansenist leanings and not being enough of a devotee to Rome.