Western European Union (WEU) came into being in 1954 through a modification of the Brussels Treaty of 1948 which set up the Brussels Treaty Organisation, also referred to as Western Union. At that time WEU consisted of the five signatories to the Brussels Treaty of 1948 (Belgium, France, Luxembourg, the Netherlands and the United Kingdom), along with the Federal Republic of Germany and Italy. The modified Brussels Treaty conferred powers on WEU in the economic, social and cultural areas but also, and in particular, in the fields of armaments and security and defence, while avoiding any overlapping with the other international organisations such as the North Atlantic Treaty Organisation (NATO), the Council of Europe, the Organisation for European Economic Cooperation (OEEC) and the European Coal and Steel Community (ECSC).
The objective at the outset was to build, eventually, a more integrated Europe and consolidate the anchoring of Germany in the Euro-Atlantic, Western world, while indirectly ‘Atlanticising’ Western European defence through the Treaty’s Article V on collective defence, which involved military implementation with NATO assistance and resources.
For a long time WEU was the only European organisation dealing with security and defence. The modified Brussels Treaty Organisation, which was gradually opened up to new members with a variety of different statuses, several times fell into a state of inertia before picking itself up and starting again. None of these revivals, though, succeeded in resolving the underlying tensions between ‘Europeanists’ and ‘Atlanticists’.
WEU was a symbol of the European Security and Defence Identity (ESDI), but it never managed to play a major part in any important military missions. Manipulated and pushed around, WEU was eventually cast aside in the interests of building up the European Security and Defence Policy (ESDP) of the European Union (EU). In 2000, WEU’s political and military functions were transferred to the EU.
Since 30 June 2011, the WEU as such ceased to exist.
This all means that to gauge the part played by WEU in the 20th century, one has to look mainly at the inheritance it passed on to the EU: politico-military policies, procedures and experience, and the experience of a culture of relations with NATO.