The art of war, as generally considered, consists of five purely
military branches,--viz.: Strategy, Grand Tactics, Logistics,
Engineering, and Tactics. A sixth and essential branch, hitherto
unrecognized, might be termed _Diplomacy in its relation to War_.
Although this branch is more naturally and intimately connected with the
profession of a statesman than with that of a soldier, it cannot be
denied that, if it be useless to a subordinate general, it is
indispensable to every general commanding an army: it enters into all
the combinations which may lead to a war, and has a connection with the
various operations to be undertaken in this war; and, in this view, it
should have a place in a work like this.

To recapitulate, the art of war consists of six distinct parts:--

1. Statesmanship in its relation to war.

2. Strategy, or the art of properly directing masses upon the theater of
war, either for defense or for invasion.

3. Grand Tactics.

4. Logistics, or the art of moving armies.

5. Engineering,--the attack and defense of fortifications.

6. Minor Tactics.

It is proposed to analyze the principal combinations of the first four
branches, omitting the consideration of tactics and of the art of
engineering.