For centuries Diegem was a lordship. The lord lived in the castle on the Woluwe, had a court of a mayor and aldermen, owned mills, farms, marshes and woods, and in the 16th century also acquired high, middle and low justice. Remarkably often the lordship passed to a new family through a marriage.
The van Diedeghem family
In 1265 Gilbert van Didenghem, vassal of the lord of Perk, lived at the first manor of Diegem; he is seen as the founder of the family. In 1338 Sir Jan van Diedeghem went with eight armed men to follow the Duke of Brabant in the war between England and France; his arms were green with a silver chief. Around 1384 Margaretha van Diedeghem brought the lordship, through her marriage to Jan van Brecht, to that Brussels patrician family.
Van Brecht and Oudart
Several Van Brechts were aldermen of Brussels. Jan van Brecht was knighted by Emperor Charles V on 23 October 1544. In 1536 he had a list drawn up of all the fiefs of the lordship, with a description of the castle: a house with water all around and a drawbridge. His son Karel van Brecht (1518-1595), burgomaster of Brussels in 1559 and 1561, bought high, middle and low justice over Diegem in 1558. He became caught up in the religious troubles, wandered far from home for years and died in Diegem on 10 June 1595.
Through his daughter Gertrudis, wife of Alexander Oudart, Diegem passed to the Oudart family. Karel Oudart founded Masses at the castle in his will of 1610. The lordship then went to his sister Maria and next to his sister Catharina, wife of Filips Happart. Catharina Oudart was much loved: dozens of girls were given her name, the little court mill of Nijpezele became the St.-Katarinamolen, and Saint Catherine even replaced Cornelius as patron saint.
The Happarts
Filips Happart bought jurisdiction again in 1626. When he died in Brussels in 1631, he was brought to Diegem with great ceremony and laid to rest beside his wife in the choir of the church; there lies the vault of the Oudart-Happart family, who ruled Diegem for a century and a half. His son Karel Gerolinus is named on the church spire of 1654. When he married Innocentia d'Altuna, the whole village turned out: little fir trees were planted from the castle to the church, the men were given beer and the women syrup.
Around 1700 the Happarts ran into money trouble. After the death of Karel Andreas Happart in 1702 his widow had the household goods and livestock sold at auction. His successor Antoon Happart was ordered again and again to pay debts, from bills of exchange to the hire of carriages. His son Jan Antoon renewed the castle gate in 1716 but still had to sell the lordship to Pieter Albert Piermans on 24 December 1756.
A barony
Empress Maria Theresa made Piermans a baron in 1757. After his death in 1758 Diegem went to his widow and then to their daughter Francisca Charlotte, widow of Maximiliaan de Lanfranchy; at her request Diegem was raised to a barony in 1763. After her came her son Carolus de Lanfranchy (1783) and her daughter Maria Coleta, wife of Philippe le Boucq de Beaudignies, a French colonel from Valenciennes who was for a time mayor of Diegem and died in 1837.
Their heirs sold the castle to Jean Jacques de Gaiffier d'Emerville. In 1846 it passed to Theodoor van Reynegom de Buzet, later to Jan Baptist van Reynegom and to Jan Baptist Donckier de Donceel, who handed it over to August Ulric Marga in 1902.
Mayor, aldermen and a pillory
The lord had a court of a mayor and sworn aldermen, chosen from his tenants and the leading families of the village. The list begins in 1394 with Willem Jans, ‘who is called van Nypeseele’; later came, among others, Vranck Goossens (1469), Cornelys Vrancx (1514), Dierick Humbeex (1603) and Jan vander Perre (1659). Only in 1507 did Diegem receive a seal of its own: a black shield with a golden lion. The castle had its own chaplaincy; as late as the 18th century a chaplain said Mass there on Sundays and feast days.
According to the oldest inhabitants, a pillory of bluestone stood before 1794 at the corner of the De Primus inn, to which convicts were said to have been tied. Nobody remembered anyone ever being put there. When the French army arrived in 1794, it was removed and replaced by a liberty tree.