Neutral ships, however, are entitled to some sort of warning that a blockade exists. Notice is therefore sent to all neutral governments, announcing the fact and stating exactly the extent of coast covered. Besides this, until the blockade has lasted for some time and thus has become generally known it is customary for the officers of the blockading fleet to visit and warn every ship that approaches, the warning, with the date, being entered upon her register. If, after that, she approaches the forbidden coast, she is liable to confiscation--though possibly great stress of weather might excuse her provided she landed no cargo. Instructions of this sort were issued by President McKinley to our squadron blockading Cuba. A reasonable time, also, was granted to ships that were lying in the blockaded ports at the time when the blockade was declared, to make their escape. President McKinley allowed thirty days for this purpose, which was unusually liberal. Nations engaged in war have sometimes assumed that they could establish a blockade by simply issuing a proclamation forbidding neutrals to approach the enemy's coast, without stationing ships to enforce it. For example, during the Napoleonic wars, France declared the whole coast of England to be blockaded at a time when she scarcely dared send out a ship from her ports, having been soundly thrashed at Trafalgar. But these "paper blockades" are a mere waste of time and ink. They are not valid, and except in the way of angry and contemptuous protest, no nation would consider them worthy of the slightest attention. If Spain, for instance, should attempt a desperate game of bluff by declaring New Orleans, New York and Boston under blockade, all neutral ships would come and go just the same, and she would meddle with them at her peril. This question--if it ever was a question--was finally decided by the epoch-making convention of the powers at the close of the Crimean war (treaty of Paris, 1856), which, along with other rules that have revolutionized naval warfare, declared that "blockades in order to be binding must be effective." This means that they must be maintained by a force actually stationed on the blockaded coast, strong enough to make it decidedly dangerous to attempt to run through. The temporary absence of some of the ships, however, either in pursuit of an enemy or on account of a violent storm, would not invalidate the blockade, and ships seeking to take advantage of such an opening would be liable to the full penalty if caught. And now a few words about "prizes"--a particularly interesting and timely theme, for during the very first week of the war our fleet captured no fewer than fifteen of them.