Concentration, in fact, implies a continual conflict between cohesion and
reach, and for practical purposes it is the right adjustment of those two
tensions--ever shifting in force--which constitutes the greater part of
practical strategy.

In naval warfare this concentration stage has a peculiar significance in
the development of a campaign, and at sea it is more clearly detached than
ashore. Owing to the vast size of modern armies, and the restricted nature
of their lines of movement, no less than their lower intrinsic mobility as
compared with fleets, the processes of assembly, concentration, and forming
the battle mass tend to grade into one another without any demarcation of
practical value. An army frequently reaches the stage of strategic
deployment direct from the mobilisation bases of its units, and on famous
occasions its only real concentration has taken place on the battlefield.
In Continental warfare, then, there is less difficulty in using the term to
cover all three processes. Their tendency is always to overlap. But at sea,
where communications are free and unrestricted by obstacles, and where
mobility is high, they are susceptible of sharper differentiation. The
normal course is for a fleet to assemble at a naval port; thence by a
distinct movement it proceeds to the strategical centre and reaches out in
divisions as required. The concentration about that centre may be very far
from a mass, and the final formation of the mass will bear no resemblance
to either of the previous movements, and will be quite distinct.

But free as a fleet is from the special fetters of an army, there always
exist at sea peculiar conditions of friction which clog its freedom of
disposition. One source of this friction is commerce protection. However
much our war plan may press for close concentration, the need of commerce
protection will always be calling for dispersal. The other source is the
peculiar freedom and secrecy of movements at sea. As the sea knows no roads