During the Crusades the whole of our continent was under arms. The struggle against the "infidel" was not simply a contest between one State and another, it was also a contest between Christian Europe and Mohammedan Asia. To be neutral in such a struggle would, according to the judgment of the time, have been equivalent to denying the faith. Within the European States, feudalism exerted no less a hindrance to the embodiment of the principle of neutrality. It would have been thought the gravest crime to loosen the bond of military service which compelled vassals to support with arms the cause of their feudal lords. It was only with the close of the age of feudalism, when Europe began to separate into three or four great monarchies, that neutrality in politics became a means of preserving the balance.
In later times increasing communication and trade have above all contributed to the development of neutral laws. Without the sanction of these, a naval war between two great nations would have made any maritime trade all but impossible. Down to the close of the last century, however, neutral rights were dependent either on national statutes or on special treaties concluded between one State and another. The law only gained certain international importance towards the close of the eighteenth century through the neutral alliances which from time to time were contracted between States.
In the period between 1780 and 1856 the subject gained an entrance by degrees among all maritime nations except England, who, independent of it, and always relying on her own strength, continuously sought to maintain unlimited domination at sea.
In 1854-56 begins, so far as neutrality is concerned, a new era of international law.
From this time the opposition which England raised to the practical application of neutrality in naval war may be regarded as having broken down. On the 30th of March, 1854, the French Minister of Foreign Affairs, Drouyn de Lhuys, published a communication, including, amongst other things, that the neutral flag during the then begun (Crimean) war, should be regarded as a protection for all neutral and hostile private property, except contraband of war. The same day the English Government gave forth in the London Gazette a similar declaration, and on April 19th of the same year the Russian Government notified in the Official Gazette of St. Petersburg that Russia would, during that war, act upon the same rules as the Allied powers.
The provisions, which thus the Western powers on one side, and Russia on the other, believed themselves bound to observe towards neutral states, were at the Peace of Paris, 1856, solemnly ratified as International Law in force for all time. The principles which the plenipotentiary signatories of the Peace Treaty of Paris agreed upon in a proclamation of April 16th, 1856, are as follows:—
1. Privateering is and shall be abolished. 2. The neutral flag shall protect property belonging to the enemy, with the exception of contraband of war. 3. Neutral goods, except contraband of war, may not be seized under the enemy's flag. 4. Blockades in order to be obligatory must be fully effectual; that is, shall be maintained with a strength really sufficient to prevent approach to the enemy's coast.
The Governments which signed the treaty bound themselves also, in this proclamation, to communicate the resolutions to the States which were not called to take part in the Paris Conference, and to invite them to agree in these decisions. All the European States except Spain, and a number of powers outside Europe, declared themselves ready to carry out in practice the entire resolutions of the proclamation.
Many wars since then have shaken Europe; but under all these misfortunes the warring States have not only conscientiously observed the principles laid down in 1856, but they have gone further, in certain points, in applying them, than they by it were bound to do. Thus the Austrian Government issued an order, during the war with France and Sardinia, with respect to maritime national law, in many points far beyond what hostile or neutral powers had any ground for requesting. The Imperial decree not only charged its military and civil officers to follow strictly the injunctions of the proclamation, but Sardinian and French vessels, which lay moored in Austrian waters, were also to be permitted to load freight and proceed to foreign seas, on condition that they took on board no contraband of war or prohibited goods of any description. Immediately on the outbreak of war, the same principles were adopted by France and Sardinia. These States, however, went a step further than Austria, inasmuch as they unreservedly declared that they would not regard coal as a contraband of war.
During the Dano-German War, in 1864, and the war between Austria and Prussia and Italy, in 1866, the international principles of maritime law received a similarly wide interpretation.