There are two kinds of blockade--military and commercial. The former includes the latter, but the latter does not necessarily involve the former, except in the sense that armed naval force is necessary to maintain it. By a commercial blockade a belligerent seeks to intercept the maritime commerce of the enemy, to prevent any vessels, whether enemy or neutral, from reaching his ports, and at the same time to prevent their egress to the same extent. This in certain circumstances may be a very effective agency for bending or breaking the enemy's will and compelling his submission, but I reserve its consideration for more detailed treatment hereafter. It is with military blockade that I am here more especially concerned. We have seen that the paramount purpose of all naval warfare, and, indeed, of all warfare, is the destruction of the armed forces of the enemy. His armed forces are in the last resort the sole instrument of his will, and their destruction to such an extent as is necessary to subdue his will is the sole agency by which peace can be restored. Whatever the extent of the war, whether it is limited or unlimited, in the sense assigned to those words by Clausewitz and his followers, the conflict of national wills out of which the quarrel arose must in some way be composed, either by concessions on both sides or by the complete subjection of one side to the other, before it can come to an end. It follows that the main object of a military blockade can rarely be to keep the enemy's forces sealed up, masked, and to that extent immobilized in the blockaded ports. Its real object is to secure that if they do come out they shall be observed, shadowed, and followed until such time as they can be encountered by a superior force, and if possible destroyed. The classical text on this topic is a letter written on August 1, 1804, by Nelson to the Lord Mayor of London, acknowledging a vote of thanks passed by the Corporation, and addressed to Nelson as commanding the fleet blockading Toulon. Nelson said in his reply: "I beg to inform your Lordship that the port of Toulon has never been blockaded by me: quite the reverse--every opportunity has been offered to the enemy to put to sea, for it is there that we hope to realize the hopes and expectations of our country, and I trust that they will not be disappointed." What Nelson here meant was that the so-called blockade of the port--it was a common, but, as he held, an erroneous expression--was merely incidental to the operation he was conducting. His main objective was the armed forces of the enemy lying unassailable within the blockaded port. He could not make them put to sea but he gave them every opportunity of doing so. So far from wishing to keep them in, his one desire was to get them out into the open, "for it is there that we hope to realize the hopes and expectations of our country"--that is to get a decision in favour of the British arms.