Being such as here described, the frigate was essentially, though not exclusively, the appendage of a fleet of line-of-battle ships. Wars are decided not by commerce destroying nor by raids, however vexatious, but by fleets and armies, by great organized masses—that is, by crushing, not by harassment. But ships of the line, to perform their function, must keep together, both when cruising and when on the field of battle, in order to put forth their strength in combination. The innumerable detached services that must be discharged for every great organized force need for a fleet to be done by vessels of inferior strength, yet so strong that they cannot be intercepted or driven off lightly by every whipper-snapper of an armed ship that comes along. Moreover, a fact not always realized, speed—speed to hasten on a mission, to overtake a foe, or to escape pursuit—depends upon size, masts that can carry sail and hold way amid heavy seas. Hence the frigate, not the lighter sloop, was indicated for the momentous duties upon which depended the intelligence and the communications of the fleet. Such leading considerations are needed to be stated and to be kept in mind, for they affected the warfare of the last decade of the century quite as really as they did that of the first, and a paper would indeed be incomplete which confined itself to indicating points of difference of progress, so-called, and failed to recognize those essential and permanent conditions which time will never remove. Frigates and sloops have disappeared in name and form, in motive power and in armament. Their essential functions remain, and will remain while war lasts. DUTIES OF THE FRIGATE The truth of this statement will be evident from a brief mention of the duties frigates actually used to perform. While attending the fleet, not merely a part of it, the frigates were thrown out far in advance and on each side, as cavalry on land scours the country towards or through which the army advances. The distance to which they would be thus detached would sometimes amount to one hundred or two hundred miles, and the absence to days, rejoining being assured by the assignment of a rendezvous, or by an adequate knowledge of the admiral’s intended movements. It will be recognized that when thus alone frigates might meet equal or superior forces, to resist or to escape from which both strength and speed were needed. An extreme and particular case of such service was the watching of an enemy’s port by one or more frigates, when they had to keep close to the entrance, although a fleet might be within. Again, frigates were placed in certain central positions, rendezvous known only to the superior officers, where they cruised steadily, having information as to the whereabouts of the fleet, or instructions for expected vessels. They were there centres of intelligence, round which the movements of the whole body revolved.