In this note drawn up for the Belgian Commission for the Study of Post-war Problems (CEPAG), Fernand Van Langenhove, Secretary-General of the Belgian Foreign Ministry, analyses the conditions required for the conclusion and the operation of a Netherlands–Belgium Customs Union.

On 21 October 1943, Belgium, Luxembourg and the Netherlands sign a monetary convention in London which sets the exchange rate between the Belgian and Luxembourg franc and the Dutch guilder and establishes a mutual funding mechanism in the event of a balance of payments deficit of one of the signatories.

On 2 November 1943, the Belgian Foreign Ministry distributes this circular which refers to the address given by Camille Gutt, Belgian Finance Minister, at the signing of the Monetary Convention between Belgium, Luxembourg and the Netherlands on 21 October 1943, in London.

On 9 September 1944, Paul-Henri Spaak, Belgian Foreign Minister, officially informs Belgian diplomats of the conclusion of a transitional agreement on a customs union between the Governments of Belgium, Luxembourg and the Netherlands.

On 5 September 1944, Belgium, Luxembourg and the Netherlands sign a Customs Convention which, together with an additional Protocol of 14 March 1947, enters into force on 1 January 1948.

On 17 and 18 April 1946, representatives of the Belgian, Luxembourg and Dutch Governments meet in The Hague to discuss the economic relations between their three countries.

On 14 March 1947, Belgium, Luxembourg and the Netherlands sign an additional Protocol to the Benelux Customs Convention, which enters into force on 1 January 1948.

Text of the Belgium–Luxembourg–Netherlands Customs Convention, signed in London on 5 September 1944, specified and interpreted in accordance with the Protocol signed in The Hague on 14 March 1947.

On 2 and 3 May 1947, representatives of the Belgian, Luxembourg and Dutch Governments meet in Brussels to discuss the economic relations between the three countries.

In a report presented to the Franco–Belgian section of the Inter-Parliamentary Union on 1 November 1947, the Belgian MP, Raymond Scheyven, calls for a customs and economic union between France and Benelux.

From 29 to 31 January 1948, representatives of the Belgian, Luxembourg and Dutch Governments meet in Luxembourg to coordinate their financial, economic and social policies.

"Unter dem Zeichen des Benelux". Am 23. März 1948 illustriert der Karikaturist Simon in der luxemburgischen Tageszeitung Tageblatt das Inkrafttreten der Benelux-Zollunion.

From 10 to 13 March 1949, representatives of the Belgian, Luxembourg and Dutch Governments meet in The Hague to discuss the introduction of an economic union between the three countries.

On 16 October 1949, Belgium, Luxembourg and the Netherlands sign the Benelux Pre-Union Treaty in Luxembourg.

On 16 October 1949, Belgium, Luxembourg and the Netherlands sign the Benelux Pre-Union Treaty in Luxembourg. The Luxembourg delegation during the talks on the Benelux Pre-Union Treaty. From left to right: Aloyse Hentgen, Minister for Agriculture and Economic Affairs, Pierre Dupong, Minister of State and President of the Luxembourg Government, and Eugène Auguste Collart, Luxembourg Special Envoy to the Netherlands.

‘Pre-union. Do you love me? No!’ On 30 October 1949, the Brussels newspaper Le Phare Dimanche portrays the tensions within the Benelux Customs Union which are dividing Belgium and the Netherlands and are based on the pre-union agreement signed two weeks earlier in order to prepare for the Benelux Economic Union.

In his memoirs, Joseph Luns, Dutch Foreign Minister from 1956 to 1971, recalls the early days of economic cooperation between the Netherlands, Belgium and Luxembourg, which eventually led to the creation of Benelux.

Stamp issued in 1969 by the Luxembourg Post Office to mark the 25th anniversary of the Benelux Customs Convention.

Stamp issued in 1972 by the Luxembourg Post Office on the 50th anniversary of the Belgium–Luxembourg Economic Union (BLEU).