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,