The principal repair, and the one most difficult to furnish, is that given by docking in suitable docks.

The size and expense of docks capable of carrying dreadnaughts and battle cruisers are so great, and their vulnerability to fire from ships and from aircraft is so extreme, that the matter of dry-docks is perhaps the most troublesome single matter connected with a naval base.
The necessity of anchorage areas for submarines is a requirement of naval bases that has only recently been felt; and the present war shows a still newer requirement in suitable grounds for aircraft.
The speed of aircraft, however, is so great that little delay or embarrassment would result if the camp for aircraft were not at the base itself.

Instead of the camp being on Culebra, for instance, it might well be on Porto Rico.

The extreme delicacy of aircraft, however, and the necessity for quick attention in case of injuries, especially injuries to the engine, demand a suitable base even more imperiously than do ships and other rugged things.
That the vessels anchored in the base should be protected from the fire of ships at sea and from guns on neighboring shores is clear.

Therefore, even if a base be hidden from the sea and far from it as is the harbor of Santiago, it must be protected by guns, or mines, or both; the guns being nearer to the enemy than are the ships in the waters of the base.