Saint-Bertin is one of the richest abbeys of the Low Countries, standing at one end of Saint-Omer opposite the collegiate church of Notre-Dame.
It holds herring tithes along the coast at Calais, Gravelines and Saint-Folquin, and the sole right to build mills over a wide stretch of the Aa marshes from Arques toward Bourbourg, confirmed by the counts. Its own lordships include Arques beside Saint-Omer and Poperinge in Flanders. Saint-Omer itself has been fought over by Philip Augustus and Count Baldwin IX; the Treaty of Péronne, sealed on 2 January 1200, gives it to Flanders.
Who holds it
- Name
- John of Ypres (Jean III)
- Title
- Abbot of Saint-Bertin
- Since
- 1186
- Confidence
- high
Abbot from 1186 to 1230 by French Wikipedia's list, a long reign spanning the war over Saint-Omer.
What it holds
- The abbey and its quarter at Saint-Omer
- Arques: the abbey's lordship next to Saint-Omer
- Poperinge: the abbey's lordship in western Flanders
- Herring tithes at Calais, Gravelines and Saint-Folquin
- Exclusive right to mills between Arques, Bourbourg and other places, confirmed by the counts
How it was acquired
Gifts of the counts of Flanders and others since the seventh century; mill and tithe rights confirmed by the counts.
How things stand that morning
Held. Saint-Omer passed into royal hands with southern Artois in 1191, but Baldwin IX's war has brought it back under Flemish control (the date of his capture of the town is not checked here); the Treaty of Péronne of 2 January 1200 gives Saint-Omer and Aire to Flanders.
Wealth
Herring, mills, the cloth trade of Saint-Omer and Poperinge, and the Aa waterways to the sea.
Threats
- War between Flanders and France over Artois
- The townsmen of Saint-Omer
Advocates and rivals
The counts of Flanders, its patrons; the town of Saint-Omer and its commune; the chapter of Notre-Dame of Saint-Omer.
What the year holds
What happened next, if nothing in play changes it. Each event carries what it depends on and what would stop it.
- 2 January 1200Treaty of Péronne: Philip Augustus and Baldwin IX make peace; Saint-Omer and Aire go to Flanders.Depends on: Both sides sealing the treaty. Stopped by: A last-minute breakdown.
- Lent 1200 (after the peace)Baldwin IX of Flanders takes the cross at Bruges (23 February 1200 in the usual account), pulling Flemish lords and churchmen toward the crusade.Depends on: The peace with France holding. Stopped by: Renewed war.
Places of note
- Abbey of Saint-Bertin: The abbey at the lower end of Saint-Omer
Where the sources disagree
Evidence: The abbot, the tithes and the mill rights come from French Wikipedia. The lordships of Arques and Poperinge are well known but not checked against a source here. The date of Baldwin's crusade vow is from general knowledge, not checked here.
On the map: Arques and Poperinge are drawn as whole modern municipalities; Poperinge's merged municipality is larger than the medieval lordship. The tithes and mill rights are not drawn.
Primary sources for Flanders
Chronicles, registers, sagas and inscriptions written in or near 1200 that cover this entry. Each has its own page with editions, translations and where to read it.
- Chronicle of Alberic of Trois-Fontaines, Alberic of Trois-Fontaines (about 1227 to 1241, at the Cistercian abbey of Trois-Fontaines in Champagne). The widest net of any Latin chronicle for 1200, compiled from dozens of sources, many now lost. Read online
- Chronicle of Andres, William of Andres (about 1220 to 1234). The chronicle and cartulary of a small abbey between Guines and Ardres, near the border of Flanders and Boulogne. Read online
- Chronicle of Hainaut, Gislebert of Mons (about 1195 to 1196). Ends in 1195, so it has no 1200 entries, but it is the indispensable background for Flanders and Hainaut: the career of Count Baldwin V of Hainaut (VIII of Flanders), his union of the two counties, the settlement with Philip over Artois, the rights, castles, fiefs and vassals of Hainaut listed by a man who ran its chancery, and the youth of Baldwin IX, who held both counties in 1200. Read online
- Chronicle of Robert of Auxerre, Robert of Auxerre (Robert of Saint-Marien) (about 1190 to 1211; continued at Saint-Marien to 1227). A universal chronicle whose last twenty years are contemporary and well informed from Burgundy and the Auxerrois. Read online
- Universal Chronicle of the Anonymous of Laon, Anonymous (an English-born canon of Laon) (about 1219). A Picard chronicle whose author had lived in England and keeps an eye on both kingdoms. Read online
- Annals of Egmond (12th century to about 1205). The house annals of Egmond, the counts of Holland's abbey, and the main native source for Holland around 1200. Read online
- Chronicle of Roger of Howden, Roger of Howden (about 1192 to 1201). The fullest single narrative for the year. Read online
- Deeds of Philip Augustus, Rigord (about 1186 to 1206, in stages). The French court's own chronicle for the year, from the monk of Saint-Denis who called himself the king's chronographer. Read online
8 more in the sources library for France and Iberia.
Sources and studies
Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.