The provisions relating to coal and iron are more important in respect of their ultimate consequences on Germany's internal industrial economy than for the money value immediately involved. The German Empire has been built more truly on coal and iron than on blood and iron. The skilled exploitation of the great coalfields of the Ruhr, Upper Silesia, and the Saar, alone made possible the development of the steel, chemical, and electrical industries which established her as the first industrial nation of continental Europe. One-third of Germany's population lives in towns of more than 20,000 inhabitants, an industrial concentration which is only possible on a foundation of coal and iron. In striking, therefore, at her coal supply, the French politicians were not mistaking their target. It is only the extreme immoderation, and indeed technical impossibility, of the Treaty's demands which may save the situation in the long-run. (1) The Treaty strikes at Germany's coal supply in four ways:-- (i.) "As compensation for the destruction of the coal-mines in the north of France, and as part payment towards the total reparation due from Germany for the damage resulting from the war, Germany cedes to France in full and absolute possession, with exclusive rights of exploitation, unencumbered, and free from all debts and charges of any kind, the coal-mines situated in the Saar Basin."[36] While the administration of this district is vested for fifteen years in the League of Nations, it is to be observed that the mines are ceded to France absolutely. Fifteen years hence the population of the district will be called upon to indicate by plebiscite their desires as to the future sovereignty of the territory; and, in the event of their electing for union with Germany, Germany is to be entitled to repurchase the mines at a price payable in gold.[37]