There was a Roman Castellum on this location, built in the 4th century, whose outline is still visible in the city's streetplan. Some of the stones of the former walls were later used in the construction of the abbey. The former abbey of St. Peter at Oudenburg, founded by Arnold of Soissons, was destroyed during the French Revolution.
1087: Death of Arnold of Soissons. (also known as Arnold of Oudenburg or Saint Arnold.)
1226: The City is represented on a Seal.
1843, February 2: The arms were granted.
The arms show a castle with the arms of the medieval Lords of Oudenburg in the gate. The castle (Burcht) is a canting element. The castle already appeared on the oldest seal of the city, dating from 1226. All later seals showed a castle, but the size and shape of the castle has changed considerably through the centuries. The small shield appeared for the first time in the 16th century.