Ancient Diocese of Boulogne explained

The former French Catholic diocese of Boulogne existed from 1567 to the French Revolution. It was created after the diocese of Thérouanne was suppressed because of war damage to the see; effectively this was a renaming. It belonged to the Archdiocese of Reims. The Concordat of 1801 suppressed the diocese of Boulogne, transferring its territory to the diocese of Arras.^[1] The seat was the Boulogne Cathedral, demolished in 1793.

Bishops

http://www.catholic-hierarchy.org/diocese/db521.html Boulogne (Diocese) [Catholic-Hierarchy]]

Book: Gams, Pius Bonifatius . Series episcoporum Ecclesiae catholicae: quotquot innotuerunt a beato Petro apostolo. 1873. Typis et Sumptibus Georgii Josephi Manz. Ratisbon. (Use with caution; obsolete)
Book: Eubel. Conradus . Hierarchia catholica, Tomus 1. 1913. Libreria Regensbergiana. Münster. second. (in Latin)
Book: Eubel. Conradus . Hierarchia catholica, Tomus 2. 1914. Libreria Regensbergiana. Münster. second. (in Latin)
Book: Gulik, Guilelmus. Eubel. Conradus . Hierarchia catholica, Tomus 3. 1923. Libreria Regensbergiana. Münster. second.
Book: Gauchat. Patritius (Patrice). Hierarchia catholica IV (1592-1667). 1935. Libraria Regensbergiana. Münster. 2016-07-06.
Book: Ritzler. Remigius. Sefrin. Pirminus. Hierarchia catholica medii et recentis aevi V (1667-1730). 1952. Messagero di S. Antonio. Patavii. 2016-07-06.
Book: Ritzler. Remigius. Sefrin. Pirminus. Hierarchia catholica medii et recentis aevi VI (1730-1799). 1958. Messagero di S. Antonio. Patavii. 2016-07-06.