The first of the lessons was that for operations in uncommanded or imperfectly commanded seas there was need of a covering squadron differentiated from the squadron in charge of transports. Its main function was to secure the necessary local command, whether for transit or for the actual operations. But as a rule transit was secured by our regular blockading squadrons, and generally the covering squadron only assembled in the theatre of operations. When therefore the theatre was within a defended terminal area, as in our descents upon the northern and Atlantic coasts of France, then the terminal defence squadron was usually also sufficient to protect the actual operations. It thus formed automatically the covering squadron, and either continued its blockade, or, as in the case of our attack on St. Malo in 1758, took up a position between the enemy's squadron and the expedition's line of operation. If, however, the theatre of operation was not within a terminal area, or lay within a distant one that was weakly held, the expedition was given its own covering squadron, in which the local squadron was more or less completely merged. Whatever, in fact, was necessary to secure the local control was done, though, as we have seen, and must presently consider more fully, this necessity was not always the standard by which the strength of the covering squadron was measured. The strength of the covering squadron being determined, the next question is the position or "tract" which it should occupy. Like most other strategical problems, it is "an option of difficulties." In so far as the squadron is designed for support--that is, support from its men, boats, and guns--it will be desirable to station it as near as possible to the objective; but as a covering squadron, with the duty of preventing the intrusion of an enemy's force, it should be as far away as possible, so as to engage such a force at the earliest possible moment of its attempt to interfere. There is also the paramount necessity that its position must be such that favourable contact with the enemy is certain if he tries to interrupt. Usually such certainty is only to be found either in touch with the enemy's naval base or in touch with your own landing force. Where the objective is the local naval base of the enemy these two points, of course, tend to be identical strategically, and the position of the covering squadron becomes a tactical rather than a strategical question. But the vital principle of an independent existence holds good, and no matter how great the necessity of support, the covering squadron should never be so deeply engaged with the landing force as to be unable to disentangle itself for action as a purely naval unit in time to discharge its naval function. In other words, it must always be able to act in the same way as a free field army covering a siege.