A warship, considered in the abstract, may be defined as a vessel employed, and generally constructed, for the purpose of conveying across the seas to the place of conflict, the weapons that are to be used in conflict, the men who are to use them, and all such stores, whether of food or other supplies, as will give to the vessel as large a measure of enduring mobility as is compatible with her displacement. If we confine our attention to the period posterior to the employment of the gun on shipboard as the principal weapon of offence, and if we regard the torpedo as a particular kind of projectile, and the tube from which it is discharged as a particular kind of gun, we may condense this definition into the modern formula that a warship is a floating gun-carriage. With the methods and implements of sea warfare anterior to the introduction of the gun we need not concern ourselves. They belong to the archæology of the subject. It suffices to point out that in all periods of naval warfare the nature of the principal weapon employed, and to some extent that of the motive power available, have not only governed the structure of the ship and determined the practicable limit of its displacement, but have also exercised a dominant influence over the ordering of fleets and their disposition in action. Sea tactics have never been more elaborate than they were in the last days of the galley period which came to an end with the Battle of Lepanto in 1571, less than a score of years before the defeat of the Armada in 1588. But the substitution of sails for oars as the motive power of the warship and the more general employment of the gun as the principal weapon of offence necessarily entailed radical changes in the tactical methods which had been slowly evolved during the galley period. At first all was confusion and a sea-fight was reduced for a time to a very disorderly and tumultuous affair. "We went down in no order," wrote an officer who was present at Trafalgar, "but every man to take his bird." This is a very inaccurate and even more unintelligent account of the tactics pursued at Trafalgar; but it might very well stand for a picturesque summary of the tactical confusion which prevailed at the period of the Armada and for half a century afterwards.