elf made a close blockade of the German
coast impossible, Great Britain in the World War steadily extended
her efforts to cut off Germany's intercourse with the overseas
world. Germany, on the other hand, while unwilling or unable to
take the risks of a contest for surface control of the sea, waged
cruiser warfare on British and Allied commerce, first by surface
vessels, and, when these were destroyed, by submarines. In the
policies adopted by each belligerent there is an evident analogy to
the British blockade and the French commerce destroying campaigns
of the Napoleonic Wars. And just as in the earlier conflict British
sea power impelled Napoleon to a ruinous struggle for the domination
of Europe, so in the World War, though in a somewhat different
fashion, the blockade worked disaster for Germany.

"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