This neutrality was recognised and guaranteed by the great European powers at the Congress of Vienna in 1815 (art. 84 and 92), and later was further solemnly confirmed by a special act of the powers at Paris, Nov. 20th of the same year, in which it was stated: "The powers declare ... by a permanent act that the permanent neutrality and inviolability of Switzerland, as well as its independence of foreign influence, accords with the true interests of European policy."[15] THE NEUTRALIZATION OF BELGIUM. In virtue of the Treaty of London, Nov. 15th, 1831 (art. vii.), further confirmed by the powers April 19th, 1839, a permanent neutrality was awarded to Belgium. This country, which for centuries had served as a battle-ground for foreign powers, especially for France and Germany, was hereby secured against such dangers, and at the same time the field for European warfare was materially narrowed. Article vii. of the London protocol runs thus: "Belgium shall, within the boundaries established in art. i. and iv., form an independent State. The kingdom is bound to observe the same neutrality towards all States."[16] During the Franco-German war 1870-1, the neutralization of Belgium was threatened with violation by France, and further guarantees were given in new protocols arranged by England. THE NEUTRALIZATION OF THE ARCHDUCHY OF LUXEMBURG resulted from the London protocol of May 11th, 1867. As an evidence of the power and importance in our day of entering into agreements of neutrality, the following may be adduced:-- During the Franco-German war, 1870-1, the Prussian Government complained to the guaranteeing powers of conduct at variance with neutrality on the part of Luxemburg, and threatened no longer to respect the neutrality of the Archduchy. (Despatch of Prince Bismarck, Dec. 3rd, 1870.) In consequence of this, Count Beust, the Austrian chancellor, in an opinion given Dec. 22nd of the same year, remarked, that upon the ground of the principle of European guarantee, it belonged to the powers who had signed the document of neutralization, to inquire into and to settle whether a violation had taken place on the part of the neutral State, and not to one of the belligerent powers.[17] Besides the States named, a permanent neutrality has been secured to the IONIAN ISLANDS according to the treaties of London, 1863-64; and also to the SAMOAN ISLANDS, in virtue of the agreement between England, Germany, and the United States of North America, whereby, amongst other things, it was settled that in case of any difference of opinion arising; an appeal should be made to arbitration; and that a supreme tribunal should be created with a supreme judge, whom the King of Sweden and Norway has been empowered to name. * * * * * One general advantage which neutralization affords is the simplification with respect to foreign policy thereby obtained.