The preëminence of the linguistic factor set forth in these pages may be illustrated concisely by the accepted recognition of the “langue d’oïl” as the national language of France by all Frenchmen of the present day, although this would have been impossible five centuries ago. Adoption of the linguistic criterion in boundary delimitation becomes, therefore, a mere matter of expediency. Its worth is not due to any assumed abstract value of language. It is merely a practical manner of settling divergences regarding national ownership of border territories. It is of value because the guiding consideration in boundary delimitation or revision is to eliminate future sources of conflict. The European war is no exception to the fact that almost every conflict of magnitude has been due, in part, to ill-adjusted frontier lines. Slight regard for national aspirations seems to have prevailed in the delimitations determined upon by the signatory powers of every important treaty. The seed of ulterior fighting was thus sown, for one of the main features of modern history is the growth of national feeling as a dominating force in human affairs. With Europe rid of Napoleon, the treaty of Vienna was framed by his allied foes in 1815 for the purpose of recasting the political map. No heed was paid, however, to the legitimate desire of smaller European nations to rule themselves. An instance of some of the gross blunders committed then was the merging of Belgium and Holland into one nationality in spite of the protests of their representatives. Feelings of the bitterest nature between Belgians and Dutch engendered by this act ultimately forced a war between the two countries in 1830. It was only after their separation that the enmity of the two peoples gave way to cordial relations. Subsequent history has shown that these two nations have often been of greater help to each other while retaining separate political entity than under forced union. In Italy also the progress made towards union by Italian-speaking peoples was checked by this treaty and the country split once more into a number of small independent states. The assignation of Lombardy and Venetia to Austria led eventually to the war of 1859.