The fusion of the Belgian municipalities (, ) was a Belgian political process that rationalized and reduced the number of municipalities in Belgium between 1964 and 1983. In 1961, there were 2,663 such municipalities; by 1983, these had been re-arranged and combined into 589 larger municipalities.

French and Dutch periods (1796–1830) The annexation by France of the Austrian Netherlands, the principalities of Liège and Stavelot-Malmedy and the Duchy of Bouillon on 4 Brumaire of Year IV of the Revolution (26 October 1795)Hervé Hasquin, La Belgique française 1792–1815, Editions Crédit Communal, 1993, p. 187 led to territorial reorganization, with the commune as the basic territorial unit. In 1800, there were 2,741 communes in what is now Belgium.Page 45. However, the French authorities wanted to reduce the number of communes in the Belgian départements, and urged the departmental prefects to take measures to that effect. A total of 127 communes were abolished during this period in the Jemappe, Dyle and Sambre-et-Meuse departments.André Tihon, "La fusion des communes dans le département de la Dyle sous le régime napoléonien", Revue belge de Philologie et d'Histoire, 1965, 43–2, p.515-551 The Dutch period did not put an end to this process, which continued to a lesser extent, so that by 1830 there were 2,492 communes.

From independence to the interwar period (1830–1940) With Belgium's independence, the trend was reversed with the creation of new communes, reaching a peak in 1928, when the country counted 2,675 communes, after 153 had been created and 7 abolished over the same period.Page 46. Thus, in 1896, the hamlet called La Bretagne separated from Landelies (part of Montigny-le-Tilleul since 1977) to become an autonomous commune under the name Goutroux. Article 3 of the Belgian Constitution as then in force (currently article 7) and the provincial law of 1836 codified the procedures for mergers or the creation of new communes in Belgium.

During this period, Belgium underwent two changes to its territorial boundaries. The Treaty of London (1839) led Belgium to cede part of its territory, forming the province of Limburg (Netherlands) and the Grand Duchy of Luxembourg. Since 1830, Belgium had administered the whole of Limburg and Luxembourg. In 1831, the Treaty of the Eighteen Articles had recognized this, but it was never signed by the Netherlands. The corresponding communes were therefore lost in 1839. After the First World War, the communes of the East Cantons were annexed from Germany.

Population movements, the rural exodus and the economic upheavals of the 19th and early 20th centuries led to new thinking on the organization of the municipal map, especially in Brussels, where there was a desire to create a "Greater Brussels".Page 47. On the eve of the First World War, two solutions were put forward: grouping the outlying communes with Brussels, or creating an inter-communal structure to manage certain responsibilities. In 1921, just after the war, the mayor of Brussels, Adolphe Max, proposed the creation of a metropolitan district for the Brussels conurbation. In the same year, the communes of Laeken, Neder-Over-Heembeek and Haren merged with Brussels to form the City of Brussels, without any consultation and consent of the concerned populations."Fusion ou annexion ? La question de la consultation populaire dans les projets d’agrandissement de la Ville de Bruxelles", Archives de Bruxelles In the interwar period, publications on communal management outlined ideas for the future of communes, including the merger of communes.Page 48.

World War II The German occupation of Belgium during World War II overturned the kingdom's municipal structure. The Germans wanted the outlying communes around major conurbations to form a single commune with a single administration and police organization As a result, several communes were grouped together, leading to the birth of seven large communes between 1941 and 1942: Antwerp, Bruges, Brussels, Charleroi, Ghent, La Louvière and Liège.Pages 48 and 49.Nico Wouters, "Grandes agglomérations", CegeSoma The legal authorities opposed these creations, and on 1 February 1943, the Court of Cassation confirmed the illegality of the creation of Greater Antwerp, despite the insistence of the occupation authorities.Page 49. The end of the German occupation put a radical end to these mergers of communes and a return to the pre-war status quo, but the idea was not abandoned.

Unitary Law In the aftermath of the Second World War, four communes were abolished between 1945 and 1961.Page 50. On 1 January 1961, there were communes in Belgium.Étienne Van Hecke, "Les fusions de communes : 1964 – 1971", Courrier hebdomadaire du CRISP, nr.540-541, 1971 A ministerial circular of 1957 and a policy declaration by the Eyskens III Government in November 1958 encouraged small communes to merge. This led to the Unitary Law of 14 February 1961, which introduced new provisions to facilitate mergers of communes by giving the government the right to carry out such regroupings for a period of ten years. These new provisions led to an initial reduction in the number of communes. In 1964, Belgium had communes, 110 of which were grouped into 37 new entities. Belgium had come to have communes by 1970, and the following year.

At the end of this ten-year period, in 1971, Lucien Harmegnies, Minister of the Interior under the Eyskens IV Government (1968–1972), decided to proceed with the remembrement of the territory and had a new law passed on 23 July 1971."23 juillet 1971. – Loi concernant la fusion des communes et la modification de leurs limites", Moniteur belge, 6 August 1971"26 juillet 1971. – Loi organisant les agglomérations et les fédérations de communes.", Moniteur belge, 24 August 1971. This broadened the scope of the Unitary Law to make it applicable in the case of large conurbations, initially excluded from these provisions.Page 51. However, no new merger proposals were put forward until June 1974.

Michel Plan and 1977 merger In September 1974, the Minister of the Interior, Joseph Michel, of the Tindemans II Government, announced the launch of the remodeling of the communal map, to be completed by the communal elections of October 1976.Page 52. Several criteria were used to group communes together, such as financial, geographical, linguistic, economic, social or cultural elements, without altering the boundaries of the administrative districts and provinces unless they were justified under the law of 23 July 1971. After consulting the provinces and communes between September 1974 and January 1975 on merger proposals, a draft merger plan was written and submitted to two regional ministerial committees, one for Wallonia and the other for Flanders.Pages 52 and 53.

This project resulted in the Royal Decree of 17 September 1975, dividing Belgium into 589 communes by 1 January 1977, but was postponed by six years for Antwerp and seven communes on its outskirts."17 septembre 1975. – Arrêté royal portant fusion de communes et modification de leurs limites", Moniteur belge, 25 September 1975.Robert Sevrin, "Les fusions de communes en Belgique", Hommes et Terres du Nord, no. 4, 1980.

This was ratified by the law of 30 December 1975."30 décembre 1975. – Loi portant : 1° ratification d’arrêtés royaux pris en exécution de la loi du 28 juillet 1971 concernant la fusion de communes et la modification de leurs limites; 2° suppression des fédérations périphériques créées par la loi du 26 juillet 1971 organisant les agglomérations et les fédérations de communes", Moniteur belge, 23 January 1976 On 1 January 1977, Belgium went from to 596 communes.

Antwerp merger and rectification of municipal boundaries (1977–1983) Following the adoption of the law of December 1975, in 1976 a special commission was set up in each province to rectify the administrative boundaries of all 596 communes.Page 53 and 54. After discussions with communes, individuals and private bodies, royal decrees were issued in 1982 to finalize the rectifications.Page 54.

Having obtained a six-year reprieve, in the course of 1982, two decrees and two laws regulated the details of the merger of the communes of Antwerp, Berchem, Borgerhout, Deurne, Ekeren, Hoboken, Merksem and Wilrijk for 1 January 1983."23 décembre 1982. – Loi ratifiant l'arrêté royal du 29 octobre 1982 complétant l'arrêté royal du 26 mars 1982 réglant certaines modalités et conséquences de la fusion des communes d'Anvers, Berchem, Borgerhout, Deurne, Ekeren, Hoboken, Merksem et Wilrijk en une nouvelle commune d'Anvers", Moniteur belge, 28 January 1983.Page 53. On 1 January 1983, Belgium comprised 589 communes, as stipulated by the law of 30 December 1975: 308 in the Flemish Region, 262 in the Walloon Region and 19 in the Brussels-Capital Region.

21st century The regionalisation of local government organisation slowly renewed the question of municipality merging, especially in Flanders. The Flemish, Walloon and Brussels Regions became responsible for their respective municipalities through the special law of 13 July 2001 transferring various powers to the regions and communities."Loi spéciale portant transfert de diverses compétences aux régions et communautés", Moniteur belge, 3 August 2001.

Brussels Region In their 13 July 2009 coalition agreement for the Brussels-Capital Region, the PS, Ecolo, cdH, Open Vld, CD&V and Groen agreed to set up a working group on the better distribution of competences between the Region and the communes and on communal borders, which would be made up of regional and communal representatives and would submit its conclusions over two years."Accord complet en Région bruxelloise", 7sur7.be, 13 July 2009. On 17 September 2010, the note concluded "Following the debate on the advisability of merging communes, the group recommends reviewing communal boundaries crossing obstacles such as railroads or roadways."Belga, "Pour un nouveau contrat Région bruxelloise – communes", RTBF, 17 September 2010.

Flanders Region The Flemish decree of 24 June 2016 on the Voluntary Merging of Municipalities created a regulated procedure, including a financial incentive for municipalities who merge.Decreet Vrijwillige Samenvoeging van Gemeenten van 24 juni 2016, Vlaamse Codex After decades without any change, some municipalities began seriously considering a fusion.

Fifteen Flemish municipalities were merged into seven as of 1 January 2019, reducing the number of Flemish municipalities from 308 to 300, and the Belgian total from 589 to 581.