abitually followed by a careful
seaman, and afford some presumption as to his movements; but in 1778
the data for such precision were not collected, and even had they
been, the quickest route must often have been abandoned for one of the
many possible ones, in order to elude pursuit or lying-in-wait. In
such a game of hide-and-seek the advantage is with the sought, and the
great importance of watching the outlets of an enemy's country, of
stopping the chase before it has got away into the silent desert, is
at once evident. If for any reason such a watch there is impossible,
the next best thing is, not attempting to watch routes which may not
be taken, to get first to the enemy's destination and await him there;
but this implies a knowledge of his intentions which may not always be
obtainable. The action of Suffren, when pitted against Johnstone, was
throughout strategically sound, both in his attack at Porto Praya and
in the haste with which he made for their common destination; while
the two failures of Rodney to intercept the convoys to Martinique in
1780 and 1782, though informed that they were coming, show the
difficulty which attended lying-in-wait even when the point of arrival
was known.

Of any maritime expedition two points only are fixed,--the point of
departure and that of arrival. The latter may be unknown to the enemy;
but up to the time of sailing, the presence of a certain force in a
port, and the indications of a purpose soon to move, may be assumed to
be known. It may be of moment to either belligerent to intercept such
a movement; but it is more especially and universally necessary to the
defence, because, of the many points at which he is open to attack, it
may be impossible for him to know which is threatened; whereas the
offence proceeds with full knowledge direct to his aim, if he can
deceive his opponent. The importance of blocking such an expedition
becomes yet more evident should it at any time be divided between two
or more ports,--a condition which may easily arise when the facilities
of a single dock-yard are insufficient to fit out so many ships in
the time allowed, or when, as in the present war, allied powers
furnish separate contingents. To prevent the junction of these
contingents is a matter of prime necessity, and nowhere can this be
done so certainly as off the ports whence one or both is to sail. The
defence, from its very name, is presumably the less strong, and is
therefore the mo