The first church was built near the castle by Heldwide, around 948, the wife of Hilduin 1st of the house of the Counts of Montdidier][REF] .
Under the Ancien Régime, Montdidier was in the province of the Santerre (one of eight provinces of Picardy) and the seat of a bailiwick (established in 1516)[REF][REF] By edict of 1575, Henry III of France created the élection of Montdidier, granting tax-raising powers to elected representatives.