"The consequences of the blockade," writes the German General von Freytag-Loringhoven, "showed themselves at once. Although we succeeded in establishing our war economics by our internal strength, yet the unfavorable state of the world economic situation was felt by us throughout the war. That alone explains why our enemies found ever fresh possibilities of resistance, because the sea stood open to them, and why victories which would otherwise have been absolutely decisive, and the conquest of whole kingdoms, did not bring us nearer peace."
For each group of belligerents, indeed, the enemy's commerce warfare assumed a vital significance. "No German success on land," declares the conservative British Annual Register for 1919, "could have ruined or even very gravely injured the English-speaking powers. The success of the submarine campaign, on the other hand, would have left the United States isolated and have placed the Berlin Government in a position to dominate most of the rest of the world." "The war is won for us," declared General von Hindenburg on July 2, 1917, "if we can withstand the enemy attacks until the submarine has done its work."
Commerce warfare at once involves a third party, the neutral; and it therefore appears desirable, before tracing the progress of this warfare, to outline briefly the principles of international law which, by a slow and tortuous process, have grown up defining the respective rights of neutrals and belligerents in naval war. Blockade is among the most fundamental of these rights accorded to the belligerent, upon the conditions that the blockade shall be limited to enemy ports or coasts, confined within specified limits, and made so effective as to create evident danger to traffic. It assumes control of the sea by the blockading navy, and, before the days of mines and submarines, it was enforced by a cordon of ships off the enemy coast. A blockade stops direct trade or intercourse of any kind.
Whether or not a blockade is established, a belligerent has the right to attempt the prevention of trade in contraband. A neutral nation is under no obligation whatever to restrain its citizens from engaging in this trade. In preventing it, however, a belligerent warship may stop, visit, and search any merchant vessel on the high seas. If examination of the ship's papers and search show fraud, contraband cargo, offense in respect to blockade, enemy ownership or service, the vessel may be taken as a prize, subject to adjudication in the belligerent's prize courts. The right of merchant vessels to carry defensive armament is well established; but resistance justifies destruction. Under certain circumstances prizes may be destroyed at sea, after removal of the ship's papers and full provision for the safety of passengers and crew.
The Declaration of London,[1] drawn up in 1909, was an attempt to restate and secure general acceptance of these principles, with notable modifications. Lists were drawn up of absolute contraband (munitions, etc., adapted obviously if not exclusively for use in war), conditional contraband (including foodstuffs, clothing, rolling stock, etc., susceptible of use in war but having non-warlike uses as well), and free goods (including raw cotton and wool, hides, and ores). The most significant provision of the Declaration was that the doctrine of continuous voyage should apply only to absolute contraband. This doctrine, established by Great Britain in the French wars and expanded by the United States in the American Civil War, holds that the ultimate enemy destination of a cargo determines its character, regardless of transshipment in a neutral port and subsequent carriage by sea or land. The Declaration of London was never ratified by Great Britain, and was observed for only a brief period in the first months of the war. Had it been ratified and observed, Germany would have been free to import all necessary supplies, other than munitions, through neutral states on her frontiers.
[Footnote 1: Printed in full in International Law Topics of the U. S. Naval War College, 1910, p. 169 ff.]
The Blockade of Germany
Unable to establish a close blockade, and not venturing at once to advance the idea of a "long range" blockade, England was nevertheless able to impose severe restrictions upon Germany by extending the lists of contraband, applying the doctrine of continuous voyage to both absolute and conditional contraband, and throwing upon the owners of cargoes the burden of proof as to destination. Cotton still for a time entered Germany, and some exports were permitted. But on March 1, 1915, in retaliation for Germany's declaration of a "war area" around the British Isles, Great Britain asserted her purpose to establish what amounted to a complete embargo on German trade, holding herself free, in the words of Premier Asquith, "to detain and take into port ships carrying goods of presumed enemy destination, ownership, or origin." In a note of protest on March 30, the United States virtually recognized the legitimacy of a long-range blockade—an innovation of seemingly wide possibilities—and confined its objections to British interference with lawful trade between neutrals, amounting in effect to a blockade of neutral ports.
As a matter of fact, in spite of British efforts, there had been an immense increase of indirect trade with Germany through neutrals. While American exports to Germany in 1915 were $154,000,000 less than in 1913, and in fact practically ceased altogether, American exports to Holland and the Scandinavian states increased by $158,000,000. This trade continued up to the time when the United States entered the war, after which all the restrictions which England had employed were given a sharper application. By a simple process of substitution, European neutrals had been able to import commodities for home use, and export their own products to Germany. Now, in order to secure supplies at all, they were forced to sign agreements which put them on rations and gave the Western Powers complete control of their exports to Germany.
The effect of the Allied blockade upon Germany is suggested by the accompanying chart. In the later stages of the war it created a dearth of important raw materials, crippled war industries, brought the country to the verge of starvation, and caused a marked lowering of national efficiency and morale.