Which thing led the tension between Dutch speaking and French speaking?

The minority French-speaking community was relatively rich and powerful. This was resented by the Dutch-speaking community who got the benefit of economic development and education much later. This led to tensions between the Dutch-speaking and French-speaking communities during the 1950s and 1960s. The tension between the two communities was more acute in Brussels. Brussels presented a special problem: the Dutch-speaking people constituted a majority in the country, but a minority in the capital.