attack on a group of transports by an active enemy might destroy it altogether. But whether a military expedition should accompany the fleet, or follow a few hundred miles behind, or delay starting until command of the sea has been achieved, it is obvious that the logistic calculations and executive measures for sending a modern fleet to a very distant place, and sustaining it there for an indefinite period, must be of the highest order of difficulty. The difficulty will be reduced in cases where there is a great probability of being able to secure a base which would be able to receive large numbers of deep-draft ships in protected waters, to repair ships of all classes that might be wounded in battle, and to store and supply great quantities of ammunition, food, and fuel. No expedition of such magnitude has ever yet been made--though some of the expeditions of ancient times, such as the naval expedition of Persia against Greece, B. C. 480, and the despatch of the Spanish Armada in more recent days, may have been as difficult, considering the meagreness of the material and engineering resources of those epochs. But even if no military force accompanies the expedition, the enormous quantities of fuel, supplies, ammunition, medical stores, etc., that will be required, especially fuel; the world-wide interest that will be centred on the expedition; the international importance attaching to it; and the unspeakable necessity that the plans shall underestimate no difficulty and overlook no factor, point with a long and steady finger at the necessity of attacking this problem promptly and very seriously, and of detailing the officers and constructing the administrative machinery needed to make the calculations and to execute the measures that the calculations show to be required. _Static Defense of the Coast_.--But besides the mobile fleet which is a nation's principal concern, strategy requires that for certain points on the coast, where large national and commercial interests are centred, arrangements shall be made for what may be termed a "static defense," by vessels, mine-fields, submarines, aircraft, etc., assigned as permanent parts of the defense of these points, analogous to forts on the land. The naval activities of this species of defense will centre on the mine-fields which it is a great part of their duty to defend. To guard these, and to get timely information of the coming of any hostile force or raiding expedition, strategy says we must get our eyes and ears well out from the land. To do this, water craft and aircraft of various kinds are needed; and they must be not only sufficiently numerous over each area to scout the waters thoroughly, but they must be adapted to their purpose, manned by adequate and skilful crews, and organized so as to act effectively together.