The Treaty of Dunkirk was signed on 4 March 1947, between France and the United Kingdom in Dunkirk (France) as a Treaty of Alliance and Mutual Assistance against a possible German attack in the aftermath of World War II.

According to Marc Trachtenberg, the German threat was a pretext for defense against the USSR.

Since the end of World War II, sovereign European countries have entered into treaties and thereby co-operated and harmonised policies (or pooled sovereignty) in an increasing number of areas, in the European integration project or the construction of Europe (French: la construction européenne).

The following timeline outlines the legal inception of the European Union (EU)—the principal framework for this unification.

The EU inherited many of its present responsibilities from the European Communities (EC), which were founded in the 1950s in the spirit of the Schuman Declaration.