Western Union (alliance)

The Western Union (WU), also referred to as the Brussels Treaty Organisation (BTO),[1] was the European military alliance established between France, the United Kingdom (UK) and the three Benelux countries in September 1948 in order to implement the Treaty of Brussels signed in March the same year.[Note 1] Under this treaty the signatories, referred to as the five powers, agreed to collaborate in the defence field as well as in the political, economic and cultural fields.

Western Union

CapitalFontainebleau, France
London, United Kingdom
Historical eraCold War
21–25 February 1948
17 March 1948
 WUDO established
28 September 1948
 Korean War breaks out
25 June 1950
 NATO absorbs WUDO
 Transformed into the WEU by the Modified Treaty of Brussels
23 October 1954
Preceded by
Succeeded by
Franco-British alliance
Western European Union
Today part of EU (CSDP)
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During the Korean War (1950–1953), the headquarters, personnel and plans of the WU's defence arm, the Western Union Defence Organisation (WUDO), were transferred to the newly established North Atlantic Treaty Organisation (NATO), providing the nucleus of NATO's command structure at the Supreme Headquarters Allied Powers Europe (SHAPE). As a consequence of the failure of the European Defence Community in 1954, the London and Paris Conferences led to the Modified Treaty of Brussels (MTB) through which the Western Union was transformed into the Western European Union (WEU) and was joined by Italy and West Germany. As the WEU's functions were transferred to the European Union's (EU) European Security and Defence Policy (ESDP) at the turn of the 21st century, the Western Union is a precursor of both NATO and the military arm of the EU.



In the aftermath of World War II there were fears of a renewal of German aggression, and on 4 March 1947 the Treaty of Dunkirk was signed by France and the United Kingdom as a Treaty of Alliance and Mutual Assistance in the event of a possible attack.

In his speech to the House of Commons on 22 January 1948, British Foreign Secretary Ernest Bevin called for the extension of the Treaty of Dunkirk to also include the Benelux countries, creating a Western Union.[2] The object was to consolidate Western Europe to satisfy the United States and to give advance notice of the eventual incorporation of Italy, and then Germany, into the Treaty.

The negotiating conference was held on 4 March 1948, a few days after the coup in Prague; thanks to this, the three smaller countries were able to persuade the others to agree to the concept of automatic and immediate mutual assistance in the event of aggression, and to the idea of setting up a regional organisation (a multilateral alliance in accordance with Article 51 of the Charter of the United Nations).

The Western Union was intended to provide Western Europe with a bulwark against the communist threat and to bring greater collective security.[3]


The Treaty of Brussels was signed on 17 March 1948 between Belgium, France, Luxembourg, the Netherlands and the United Kingdom, and was an expansion to the preceding year's defence pledge, the Dunkirk Treaty signed between Britain and France.

1949 and 1950 posters advertising the Gloster Meteor jet fighter as the spearhead of Western Union defence

Although the Treaty goes no further than providing for 'cooperation' between the contracting parties, 'which will be effected through the Consultative Council referred to in Article VII as well as through other bodies', in practice the arrangement was referred to as Western Union or the Brussels Treaty Organisation.

Cannibalisation and marginalisation

When the division of Europe into two opposing camps became unavoidable, the threat of the U.S.S.R. became much more important than the threat of German rearmament. Western Europe, therefore, sought a new mutual defence pact involving the United States, a powerful military force for such an alliance. The United States, concerned with containing the influence of the U.S.S.R., was responsive. Secret meetings began by the end of March 1949 between American, Canadian and British officials to initiate the negotiations that led to the signing of the North Atlantic Treaty on 4 April 1949 in Washington, D.C.

The need to back up the commitments of the North Atlantic Treaty with appropriate political and military structures led to the creation of the North Atlantic Treaty Organisation (NATO). In December 1950, with the appointment of General Eisenhower as the first Supreme Allied Commander Europe (SACEUR), the members of the Treaty of Brussels decided to transfer the headquarters, personnel, and plans of the Western Union Defence Organisation (WUDO) to NATO.[4] NATO's Supreme Headquarters Allied Powers Europe (SHAPE) took over responsibility for the defence of Western Europe, while the physical headquarters in Fontainebleau were transformed into NATO's Headquarters, Allied Forces Central Europe (AFCENT).[5][6][7][8] Field Marshal Bernard Montgomery resigned as Chairman of WUDO’s Land, Naval and Air Commanders-in-Chief Committee on 31 March 1951 and took the position of Deputy Supreme Allied Commander Europe (DSACEUR) on 1 April 1951.

The establishment of NATO, along with the signing of a succession of treaties establishing the Organisation for European Economic Cooperation (April 1948), the North Atlantic Treaty Organisation (April 1949), the Council of Europe (May 1949) and the European Coal and Steel Community (April 1951), left the Western Union and its founding Treaty of Brussels devoid of much of its authority.

Transformation into the Western European Union

The Western Union's founding Treaty of Brussels was amended at the 1954 Paris Conference as a result of the failure of the Treaty establishing the European Defence Community (EDC) to gain French ratification: The General Treaty (German: Deutschlandvertrag) of 1952 formally named the EDC as a prerequisite to the end of Allied occupation of Germany, and there was a desire to include Germany in the Western defence architecture. The Modified Brussels Treaty (MBT) transformed the Western Union into the Western European Union (WEU), at which point Italy and Germany were admitted. Although the WEU established by the MBT was significantly less powerful and ambitious than the original Western Union, German membership in the WEU was considered sufficient for the occupation of the country to end in accordance with the General Treaty.[9]

Social and cultural aspects were handed to the Council of Europe to avoid duplication of responsibilities within Europe.[10]

In force:
Rome &
Maastricht Treaty
Three pillars of the European Union:  
European Communities
(with common institutions)
European Atomic Energy Community (EURATOM)   
European Coal and Steel Community (ECSC) Treaty expired in 2002 European Union (EU)
    European Economic Community (EEC)   European Community (EC)
        Schengen Rules  
    Terrorism, Radicalism, Extremism and Violence Internationally (TREVI) Justice and Home Affairs
  Police and Judicial Co-operation in Criminal Matters (PJCC)
  European Political Cooperation (EPC) Common Foreign and Security Policy (CFSP)
Franco-British alliance Western Union (WU)
(Cannibalised militarily by NATO in 1951)
Western European Union (WEU)
(Social and cultural activities transferred to the Council of Europe in 1960)
Treaty terminated in 2011    

Social, cultural initiative

The Treaty of Brussels had cultural and social clauses, concepts for the setting up of a 'Consultative Council'. The basis for this was that a cooperation between Western nations would help stop the spread of Communism.

Defence Organisation

Western Union Defence Organisation
Active28 September 1948[11]
Disbanded20 December 1951
United Kingdom
BranchNavy (UNIMER)
Air force (UNITER)
TypeMultinational military organisation
Sizec. 100 officers and 300 other personnel[12]
Part ofWestern Union
Garrison/HQFontainebleau, France
EngagementsCold War
CinC Comm. ChairmanFM Montgomery
CinCLandGen. Lattre
CinCAirACM Robb
FOWEVice-Adm. Jaujard

From April 1948, the member states of the Western Union decided to create a military agency under the name of the Western Union Defence Organisation (WUDO). WUDO was formally established on September 27–28, 1948.[5][13][14]


The objective of WUDO was to provide for the coordination of defence between the five powers in the military and supply fields and for the study of the tactical problems of the defence of Western Europe; in addition, to provide a framework on which, in the event of any emergency, a command organization could be built up.

The Treaty of Brussels contained a mutual defence clause as set forth in Article IV:

If any of the High Contracting Parties should be the object of an armed attack in Europe, the other High Contracting Parties will, in accordance with the provisions of Article 51 of the Charter of the United Nations, afford the Party so attacked all the military and other aid and assistance in their power.[15]

Article V set forth the obligations of Brussels Pact members to cooperate with the United Nations Security Council to maintain international peace and security, and Article VI set forth the obligations of Brussels Pact members to not enter any third-party treaties that conflicted with the Treaty of Brussels.[15]


WUDO's organisational chart as of November 1948, in which solid and dashed lines indicate control and liaison lines, respectively[16]:

Consultative Council
(foreign or prime ministers)
Permanent Commission (4 ambassadors in London plus Foreign Office representative)
Defence Committee (defence ministers)
Military Supply Board
Chiefs of Staff Committee (WUCOS)
Finance Committee
UN General Assembly Special Committee
Security Committee
Military Committee and Combined Staff of WUCOS
Commanders-in-Chief Committee and its Chairman
C-in-C Western Europe Land Forces
C-in-C Western Europe (Tactical) Air Force
Flag Officer Western Europe


Fixed locations of WUDO:
London: Defence Committee, Military Supply Board, Chiefs-of-Staff Committee
Fontainebleau: Commanders-in-Chief Committee

The overall command structure was patterned after the wartime Supreme Headquarters Allied Expeditionary Force (SHAEF), which included a joint planning staff.[13] WUDO could also be compared with the defence organisation in the United Kingdom.

Defence Committee

Government direction and control is provided by the Western Union Defence Committee which, in peacetime, was composed of the national defence ministers. The Defence Committee was served by the Chiefs-of-Staff Committee and the Military Supply Board, meeting regularly in London. These bodies were analogous to the U.K.'s Chiefs of Staff Committee and Joint War Production Staff, respectively.


The secretariat worked for the other bodies, and had a British Secretary General.

Military Supply Board

In parallel with this Chiefs-of-Staff organisation, the Western Union Military Supply Board advised the Defence Committee on all questions affecting military supplies and made recommendations as to how the requirements of the Five Powers for Military Supplies could be met. The Supply Board was on a high level and is composed of one representative from each country. The British representative, who was to be chairman for the first year, is also Chairman of the British Joint War Production Staff. The infrequent meetings of the Board were served by a permanent Executive Committee working in London, composed of representatives from each country.

Chiefs-of-Staff Committee

The Western Union Chiefs of Staff Committee (WUCOS), based in London, United Kingdom,[17] consisted of the five national chiefs of staff.[18]

WUCOS directed the operative organisation and advised the Defence Committee on all matters affecting the defence of Western Europe, taking account of commitments in other parts of the world. Within this broad direction, its special tasks in Western Europe were those such as:

  • ensuring that the military resources of the five countries were organized to meet the strategic requirements of the Allies
  • ensuring the forces of the various nations were welded into an effective fighting machine
  • ensuring their combined resources were allotted in the best way
  • maintaining a proper balance between the conflicting requirements of internal security and home defence on the one hand, and the European battle on the other
  • evaluation, preparation and distribution of the necessary resources, in particular to the Commander of the European battle, whose special task was to make the necessary operational plans and put them into operation
  • keeping constantly under review definition of the exact area of the responsibility of the command of the European battle in war

WUCOS included observers from the United States and Canada. This American liaison mission was initially led by Major General Lyman L. Lemnitzer, U.S. Army, and subsequently by Major General A. Franklin Kibler, USA.[19]

Commanders-in-Chief Committee

The Western Union Commanders-in-Chief Committee, responsible to the Western Union Chiefs-of-Staff Committee, was created on 5 October 1948.[6][21]

The committee consisted of Western Union Commanders-in-Chief for the three military branches (Land, Naval and Air), as well as the senior officer, designated Chairman. Their immediate task was to study the tactical problems of the defence of Western Europe, i.e. make plans to meet a Russian armed threat in Western Europe. They did not assume executive command of any forces in peacetime, although they were in close contact with Military Governors of the occupation zones, and it was hoped that, to a limited extent, peacetime dispositions could be adjusted to meet the needs of defence.

Members of the Western Union Commanders-in-Chief Committee
Portrait Name Title Defence branch Nationality
Field Marshal Bernard Montgomery.[19] Chairman British Army United Kingdom
General Jean de Lattre de Tassigny Commander-in-chief, Land Forces, Western Europe (CinCLand) French Army France
Air Chief Marshal Sir James Robb Commander-in-chief, Air Forces, Western Europe (CinCAir) Royal Air Force United Kingdom
Vice-Admiral Robert Jaujard Flag Officer, Western Europe (FOWE)[13][22][23] French Navy France

The committee formed a nucleus command organisation in the French town of Fontainebleau, south of Paris, known as the Combined Allied Command of WUDO (UNILION), which, in war, would be capable of commanding all land forces and supporting air forces to meet a Russian armed threat. UNILION employed c. 100 officers and 300 other personnel.[12]

The top-level headquarters of UNILION, with the office of the C-in-C Committee Chairman, was housed in Château des Fougères in Fontainebleau's neighbouring commune of Avon.[20][24]

The Henry IV quarter at the Palace of Fontainebleau
(48°24′10″N 2°42′8″E) housed the air, sea and land commands
of the Combined Allied Command. Prior to World War II these
offices housed the Artillery School.

UNILION's three subordinate commands, one for each service, were housed in the Henri IV quarter at the Palace of Fontainebleau:

  • Sea Command (UNIMER)
  • Air Command (UNIAIR)
  • Land Command (UNITER)

Much ill-feeling was caused in the headquarters from disagreements between Chairman Montgomery and CinCLand de Lattre.[25][26]

Château de Courances served as private residence for Chairman Montgomery.[6][7][23]

Operational history


The Western Union undertook the following training exercises (incomplete list):

Planned clandestine operations

  • Operation Gladio, a clandestine "stay-behind" operation preparing for, and implementing, armed resistance in the event of a Warsaw Pact invasion and conquest.

See also


  1. Although the Treaty goes no further than providing for 'cooperation' between the contracting parties, 'which will be effected through the Consultative Council referred to in Article VII as well as through other bodies', in practice the arrangement was referred to as Western Union or the Brussels Treaty Organisation.
  2. There is no documentary evidence that this ground military exercise ever took place.
  1. https://www.bbc.co.uk/news/special/politics97/news/06/0616/jargon.shtml
  2. https://www.cvce.eu/content/publication/2002/9/9/7bc0ecbd-c50e-4035-8e36-ed70bfbd204c/publishable_en.pdf
  3. https://www.cvce.eu/en/collections/unit-content/-/unit/d5906df5-4f83-4603-85f7-0cabc24b9fe1/051bd03c-4887-4f53-82eb-0f12e59f8dbd
  4. Hansard extract February 18, 1957
  5. Duke, Simon (2000). The elusive quest for European security: from EDC to CFSP. Basingstoke, UK: Palgrave Macmillan. pp. 13–14. ISBN 978-0-312-22402-8. Retrieved 2010-11-27.
  6. "Did you know that Europe already had a defensive military alliance prior to NATO?". Allied Command Operations (ACO). NATO. 2010. Retrieved 2010-08-08.
  7. Kaplan, Lawrence S. (2007). NATO 1948: the birth of the transatlantic Alliance. Lanham, Maryland: Rowman & Littlefield Publishers, Inc. pp. 139–165. ISBN 0-7425-3917-2. Retrieved 2010-08-08.
  8. "Brussels Treaty Organisation (Resolution)". Hansard. London: House of Commons of the United Kingdom. 565. 18 February 1957. cc19-20W. Retrieved 2010-11-27.
  9. Text of Modified Brussels Treaty on the WEU website at http://www.weu.int/Treaty.htm#1 (Accessed 22 Feb 18)
  10. The Western European Union On CVCE website
  11. "Multinational Commands". Air of Authority - A History of RAF Organisation. RAFWeb.org. 6 November 2007. Retrieved 2010-11-27.
  12. "LIFE". 1949-04-25.
  13. Maloney, Sean M. (1995). Secure Command of the Sea: NATO Command Organization and Planning for the Cold War at Sea, 1945-1954. Annapolis, Maryland: Naval Institute Press. pp. 66–67. ISBN 1-55750-562-4.
  14. Cichock, Mark A. (1977). "Chronology of Major European Events, 1815-1985". University of Texas at Arlington. Retrieved 2010-11-27. Compiled by Dr. James A. Kuhlman, University of South Carolina, 1977; edited by Dr. Mark A. Cichock, University of Texas at Arlington.
  15. "Treaty of Brussels". European Navigator. 17 March 1948. Retrieved 2010-11-27.
  16. https://history.state.gov/historicaldocuments/frus1948v03/d183
  17. Miller, David (2015-03-17). The Cold War: A Military History. ISBN 9781466892279.
  18. Sean Maloney, 'To Secure Command of the Sea,' the University of New Brunswick thesis 1991, p.95-97 and Lord Ismay, NATO: The First Five Years
  19. Barlow, Jeffrey G. (2009). From Hot War to Cold: the U.S. Navy and National Security Affairs, 1945–1955. Palo Alto, California: Stanford University Press. p. 209. ISBN 9780804756662. Retrieved 2010-08-20.
  20. http://www.avon77.com/IMG/pdf/Elan47.pdf
  21. Mead, Richard (2007). Churchill's Lions: A biographical guide to the key British generals of World War II. Stroud (UK): Spellmount. p. 309. ISBN 978-1-86227-431-0.
  22. Lord Ismay, Secretary General of the North Atlantic Treaty Organization, NATO—The First Five Years: 1949–1954, Edited by NATO International Archives Section, Online ed. (Paris: NATO, March 2001), c. 1; Field Marshal The Viscount Montgomery of Alamein, “The Western Union & its Defence Organization,” Lecture, The Royal United Service Institution (RUSI), London, October 12, 1949, Chaired by Marshal of the Royal Air Force Lord Newal, The RUSI Journal 138, 4 (August 1993): 52–59.
  23. Lord Ismay (December 6, 2001). "Origins of the North Atlantic Treaty: The Brussels Treaty". NATO: The First Five Years. NATO. Retrieved 2010-08-09.
  24. http://www.avon77.com/IMG/pdf/sauvons_bellefontaine.pdf
  25. Volume 3 of Nigel Hamilton's Life of Montgomery of Alamein gives a good account of these disagreements.
  26. https://www.britishpathe.com/video/western-union-defence-chiefs-deny-split-aka-disuni/query/%22Western+Union%22
  27. "WESTERN UNION: Exercise Verity". TIME. 1 July 1949. Retrieved 2010-08-06.
  28. Heathcote, Thomas Anthony (2002). The British Admirals of the Fleet 1734 - 1995, A Biographical Dictionary. Barnsley: Pen & Sword Ltd. p. 162. ISBN 0-85052-835-6. Retrieved 2010-08-08.
  29. https://www.britishpathe.com/video/exercise-cupola-western-union-air-exercises/query/%22Western+Union%22
  30. https://www.youtube.com/watch?v=W8yA2UqJ7Y4

Further reading

  • The Western Union and its Defence Organization, RUSI Journal, 94:576, 519-535 (1949), DOI: 10.1080/03071844909419583
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