From 1839 till 1914, Belgium lived under the régime of independent neutrality.
Her territory had been gradually reduced during modern times. She stood stripped of all her marches. In the course of the seventeenth century she had lost Walloon Flanders and Artois to France and Northern Brabant to Holland, while the conquest by the latter Power of Zeeland Flanders and some districts in Eastern Limburg had been confirmed and enlarged by the 1839 settlements. In 1816 Prussia had seized the districts of Eupen, Malmédy, St. Vith and Bitsburg, and the XXIV Articles had given half of Luxemburg to the German Confederation.
The same treaty granted Belgium independence. Within these narrow limits, she remained at least mistress of her destinies. She had her own king, her own Government, her own Constitution. As far as internal affairs were concerned, she enjoyed full sovereignty. She was diminished, but not deeply altered. She maintained, in the nineteenth century, all the main characteristics which had distinguished her history and civilization during the Middle Ages and the Renaissance. Two races, two languages, were still associated on her soil. Walloons and Flemings took an equal share in the framing of her future. The sea remained free for commercial purposes, and the great European roads, which had so largely contributed in the past to placing her in the forefront of European nations, still found in the country their natural and necessary meeting-place. This main fact must be made evident if one attempts to explain the causes of the Belgian renaissance during the nineteenth century. It is not enough to say that the Belgium of Leopold I and Leopold II followed the tradition of the Belgium of Charles V and Philip the Good. It must be added that modern Belgium, in spite of gradual encroachments, had remained whole. Such encroachments having taken place on all sides, the nucleus was untouched. Belgium preserved her great towns and her main streams. No essential organ of the national body had been impaired.
As far as internal affairs were concerned, Belgium then emerged free and sound from the turmoil of three centuries of European warfare. For external affairs, she was still subjected to the restriction of guaranteed neutrality. It is scarcely necessary to dwell on the distinction between self-imposed neutrality, such as that existing in Switzerland, and the régime of guaranteed neutrality imposed by the Powers on Belgium. The first is no restriction of the sovereign rights of the State upon its foreign policy, the second takes away from it practically all initiative in foreign matters. If the Powers bound themselves, in the 1839 treaty, not to violate the integrity of Belgian territory and to defend the country in case of attack, Belgium, on her side, undertook to observe strictly the rules of neutrality and to take necessary measures towards the defence of her frontiers. It might be argued, and it has been argued frequently in Belgium, that such neutrality could not prevent a nation from possessing colonies and concluding a defensive alliance for the sole purpose of safeguarding herself. But, as a matter of fact, rival Powers could not give such a liberal interpretation to the text of the treaties. First from the French side, later from the German side, Belgium was constantly held under suspicion. Any manifestation of public opinion concerning foreign affairs was deeply resented, her military policy was narrowly watched, she could not take a step towards self-defence or economic expansion without provoking some discontent among the Powers. Thanks to the firmness of her statesmen and, more than once, to the friendly support of Great Britain, she was able to resist urgent demands. But it goes without saying that the Belgian Government, anxious to preserve their dignity, avoided all possible cause of friction, so that Belgium scarcely ever made use of her legitimate right to determine, within some limits, her foreign policy. Neutrality, to all intents and purposes, meant paralysis. For many, it meant worse than that--carelessness and apathy.