At this point in the evolution of the ironclad it is convenient to bring our survey to an end. The _Collingwood_ marks the final return (with one or two notorious exceptions) to the truly broadside ship, the ship with armament symmetrically disposed fore and aft, intended to fight with others in the line. From the Admiral class onwards the modern battleship evolved for years along a continuous and clearly defined curve of progression. It only remains to close this brief and necessarily superficial historical sketch with a few remarks upon the classification of warships. In tracing the types of ironclads which superseded each other in direct succession, no mention has been made of other than those which formed in their time the chief units of naval force. Other war-vessels there were, of course, subsidiary to the main fighting force, whose value and functions we now briefly indicate. So long as sails remained the sole motive power, warships retained the same classification as they had received in the seventeenth century. “Up to the time of the Dutch Wars,” says Admiral Colomb, “ships were both ‘royal’ and of private contribution; of all sorts and sizes and ‘rates.’ Fighting was therefore promiscuous. Fleets sailed in the form of half-moons, or all heaped together and, except for the struggle to get the weather gage, there were no tactics. Actions were general.” Then, in order to protect their fleets from the fire ship, the Dutch first introduced the Line of Battle: “in which formation it was easy for a fleet to leeward to open out so as to let a fire ship drift harmlessly through.” And so the efficacy of the fire ship was destroyed. “But now, with a Line, each ship had a definite place which she could not quit. Hence the diversities in sizes began to be eliminated. The weakest ships, which might find themselves opposite the strongest, were dropped for ships ‘fit to lie in the line,’ i.e. for what were afterwards called ‘line-of-battle ships.’ These ships would be individually as powerful as possible, only subject to the objection of putting too many eggs in one basket. Uniformity would thus be attained. The fleet of line ships, however, required look-outs or scouts, which could keep the seas and attend, yet out-sail, the fleet. Hence the heavy frigate. Lastly, there was the much lighter attendant on commerce (either by way of attack or defence), the light cruiser.”