The treatment of neutrality by Grotius shows, on the one hand, that apart from the recognition of the fact that third parties could remain neutral, not many rules regarding the duties of neutrals existed, and, on the other hand, that the granting of passage to troops of belligerents and the supply of provisions to them was not considered illegal. And the practice of the seventeenth century furnishes numerous instances of the fact that neutrality was not really an attitude of impartiality, and that belligerents did not respect the territories of neutral States. Thus, although Charles I. remained neutral, the Marquis of Hamilton and six thousand British soldiers were fighting in 1631 under Gustavus Adolphus. "In 1626 the English captured a French ship in Dutch waters. In 1631 the Spaniards attacked the Dutch in a Danish port; in 1639 the Dutch were in turn the aggressors, and attacked the Spanish Fleet in English waters; again, in 1666 they captured English vessels in the Elbe...; in 1665 an English fleet endeavoured to seize the Dutch East India Squadron in the harbour of Bergen, but were beaten off with the help of the forts; finally, in 1693, the French attempted to cut some Dutch ships out of Lisbon, and on being prevented by the guns of the place from carrying them off, burnt them in the river."[531]
[531] See Hall, § 209, p. 604.
Progress of Neutrality during the Eighteenth Century.
§ 288. It was not until the eighteenth century that theory and practice agreed upon the duty of neutrals to remain impartial, and the duty of belligerents to respect the territories of neutrals. Bynkershoek and Vattel formulated adequate conceptions of neutrality. Bynkershoek[532] does not use the term "neutrality," but calls neutrals non hostes, and he describes them as those who are of neither party—qui neutrarum partium sunt—in a war, and who do not, in accordance with a treaty, give assistance to either party. Vattel (III. § 103), on the other hand, makes use of the term "neutrality," and gives the following definition:—"Neutral nations, during a war, are those who take no one's part, remaining friends common to both parties, and not favouring the armies of one of them to the prejudice of the other." But although Vattel's book appeared in 1758, twenty-one years after that of Bynkershoek, his doctrines are in some ways less advanced than those of Bynkershoek. The latter, in contradistinction to Grotius, maintained that neutrals had nothing to do with the question as to which party to a war had a just cause; that neutrals, being friends to both parties, have not to sit as judges between these parties, and, consequently, must not give or deny to one or other party more or less in accordance with their conviction as to the justice or injustice of the cause of each. Vattel, however, teaches (III. § 135) that a neutral, although he may generally allow the passage of troops of the belligerents through his territory, may refuse this passage to such belligerent as is making war for an unjust cause.
[532] Quaest. jur. publ. I. c. 9.
Although the theory and practice of the eighteenth century agreed upon the duty of neutrals to remain impartial, the impartiality demanded was not at all a strict one. For, firstly, throughout the greater part of the century a State was considered not to violate neutrality in case it furnished one of the belligerents with such limited assistance as it had previously promised by treaty.[533] In this way troops could be supplied by a neutral to a belligerent, and passage through neutral territory could be granted to his forces. And, secondly, the possibility existed for either belligerent to make use of the resources of neutrals. It was not considered a breach of neutrality on the part of a State to allow one or both belligerents to levy troops on its territory, or to grant Letters of Marque to vessels belonging to its commercial fleet. During the second half of the eighteenth century, theory and practice became aware of the fact that neutrality was not consistent with these and other indulgences. But this only led to the distinction between neutrality in the strict sense of the term and an imperfect neutrality.
[533] See examples in Hall, § 211.
As regards the duty of belligerents to respect neutral territory, progress was also made in the eighteenth century. Whenever neutral territory was violated, reparation was asked and made. But it was considered lawful for the victor to pursue the vanquished army into neutral territory, and, likewise, for a fleet to pursue[534] the defeated enemy fleet into neutral territorial waters.
[534] See below, §§ [320] and [347 (4)].
First Armed Neutrality.