rrounded,) since the supposition is that no concert of
action has been arranged with the armies operating on the other fields.
If, on the contrary, there be concert of action, the theater of
operations of each army taken singly is but a zone of operations of the
general field, occupied by the masses for the attainment of a common
object.

Independently of its topographical features, each theater upon which one
or more armies operate is composed, for both parties, as follows:--

1. Of a fixed base of operations.

2. Of a principal objective point.

3. Of fronts of operations, strategic fronts, and lines of defense.

4. Of zones and lines of operations.

5. Of temporary strategic lines and lines of communications.

6. Of natural or artificial obstacles to be overcome or to oppose to the
enemy.

7. Of geographical strategic points, whose occupation is important,
either for the offensive or defensive.

8. Of accidental intermediate bases of operations between the objective
point and the primary base.

9. Of points of refuge in case of reverse.

For illustration, let us suppose the case of France invading Austria
with two or three armies, to be concentrated under one commander, and
starting from Mayence, from the Upper Rhine, from Savoy or the Maritime
Alps, respectively. The section of country which each of these armies
traverses may be considered as a zone of the general field of
operations. But if the army of Italy goes but to the Adige without
concerted action with the army of the Rhine, then what was before but a
zone becomes for that army a theater of operations.

In every case, each theater must have its own base, its own objective
point, its zones and lines of operations connecting the objective point
with the base, either in the offensive or the defensive.

It has been taught and published that rivers are lines of operations
_par excellence._ Now, as such a line must possess two or three roads to
move the army within the range of its operations, and at least one line
of retreat, rivers have been called lines of retreat, and even lines of
maneuver. It would be much more accurate to say that rivers are
excellent lines of supply, and powerful auxiliaries in the establishment
of a good line of operations, but never the line itself.

It has also been maintained that, could one create a country expressly
to be a good theater of war, converging roads would be avoided, because
they facilitate invasion. Ever