 In 1803 the diocese was suppressed by Pope Pius VII, by the Bull, "Gravissimis causis" (1 June 1803), under pressure from the French Government of First Consul N. Bonaparte, and united with the diocese of Alessandria.In a decree of 17 July 1805, however, Cardinal Giovanni Battista Caprara, the Papal Legate in Paris, who had been given special powers by Pius VII, redrew the boundaries of the dioceses of Piedmont, and made Tortona a part of the diocese of Casale, which was made a suffragan of the diocese of Turin.The former diocese of Tortona was made part of the French department of Marengo.