The European Security and Defence Identity ESDI is an evolving concept. While its underlying philosophy dates perhaps as far back as the aborted European Defence Community initiative of 1952, its current day manifestation is a product of the post-Cold War phase of the European Union's EU development. Today, ESDI finds its expression in separate institutional frameworks in terms of a complexity of relationships between the Western European Union WEU , EU and NATO. This is the result of a grand compromise of sorts, produced by one of the hardest fought battles in Europe –the battle of Maastricht of 1991. Like most compromises, it represents half-fulfiled expectations for most of the parties involved, with certain fundamental questions deferred for the present.