ST. OMER, a town and fortress of northern France, capital of an arrondissement in the department of Pas-de-Calais, 42 m. W.N.W. of Lille on the railway to Calais. Pop. (1931) 15,886.
Omer, bishop of Therouanne, in the 7th century established the monastery of St. Bertin, from which that of Notre Dame was an offshoot. In the 9th century the village which grew up round the monasteries was named St. Omer. In 1559 St. Omer became a bishopric and Notre-Dame was raised to the rank of cathedral. The town and monastery were surrounded by walls by 980. Situated on the borders of frequently disputed territories, St. Omer long continued subject to siege and military disaster. In 1071 Philip I. and Count Arnulf III. of Flanders were defeated at St. Omer by Robert the Frisian. In 1127 the town received a communal charter from William Clito, count of Flanders. In 1493 it came to the Low Countries as part of the Spanish dominion. In 1677, after 17 days' siege, Louis XIV. forced the town to capitulate; and the peace of Nijmwegen permanently confirmed the conquest. In 1711 St. Omer, on the verge of sur rendering to Prince Eugene and the duke of Marlborough, owing to famine, was saved by the daring of Jacqueline Robin, who brought provisions into the place. St. Omer ceased to be a bishopric in 18oi.
At St. Omer begins the canalized portion of the Aa, which reaches the sea at Gravelines, and under its walls connects with the Neuffosse canal, which ends at the Lys. There are two har bours outside and one within the city. The old cathedral belongs almost entirely to the 13th, i4th and 15th centuries. A heavy square tower finished in 1499 surmounts the west portal. The church contains interesting paintings, a colossal statue of Christ seated between the Virgin and St. John (13th century, originally
belonging to the cathedral of Therouanne) and the cenotaph of St. Omer (13th century). The richly decorated chapel in the transept contains a wooden figure of the Virgin (12th century), the object of pilgrimages. Some arches and a lofty tower are all that remain of the abbey church of St. Bertin. St. Sepulchre (i4th century) has a beautiful stone spire and stained-glass win dows. There is a fine collection of records in the town hall, which was built of the materials of the abbey of St. Bertin. There are several houses of the 16th and 17th centuries; of the latter the finest is the Hotel Colbert, once the royal lodging. St. Omer is the seat of a sub-prefect, of a court of assizes, of a tribunal of com merce, of a chamber of commerce, and of a board of trade arbi trators. It was the British Headquarters during part of the World War. The industries include the manufacture of linen goods, sugar, soap, tobacco-pipes and mustard, the distilling of oil and liqueurs, dyeing, salt-refining, malting and brewing.
The suburb of Haut Pont to the north of St. Omer is inhabited by a special stock, which has remained faithful to the Flemish tongue, its original costume and its peculiar customs, and is dis tinguished by honesty and industry. The ground which these people cultivate has been reclaimed from the marsh, and the legres (i.e., the square blocks of land) communicate with each other only by boats floated on the ditches and canals that divide them. At the end of the marsh, on the borders of the forest of Clairmarais, are the ruins of the abbey founded in 114o by Thierry d'Alsace, to which Thomas Becket betook himself in 1165.