the strategic object of
the battle; or, by a combination of these. For example, when one wing of
the enemy rests on a height that commands the remainder of his line,
this would seem the decisive point to be attacked, for its occupation
would secure the greatest advantages; but this point may be so very
difficult of access, or be so related to the strategic object as to
render its attack out of the question. Thus it was at the battle of
Bautzen: the left of the allies rested on the mountains of Bohemia,
which were difficult of attack, but favorable for defence; moreover,
their only line of retreat was on the right, which thus became the point
of attack for the French, although the topographical and tactical key of
the field was on the left.

III. It frequently happens in modern warfare that battles result from
the meeting of armies in motion, both parties acting on the offensive.
Indeed, an army that is occupying a defensive position may, on the
approach of the enemy, advance to meet him while on the march. Battles
of this kind may partake of the mixed character of offensive and
defensive actions, or they may be of the nature of a surprise to both
armies. To this class belong the battles of Rosbach, Eylau, Lutzen,
Luzzara, Abensberg, &c.

Surprises were much more common in ancient than in modern times, for the
noise of musketry and the roar of artillery, belonging to the posts or
wings assailed, will prevent any general surprise of an army. Moreover,
the division into separate masses, or _corps d'armee,_ will necessarily
confine the surprise to a part, at most, of the forces employed.
Nevertheless, in the change given to military terms, a surprise may now
mean only an unexpected combination of manoeuvres for an attack, rather
than an actual falling upon troops unguarded or asleep. In this sense
Marengo, Lutzen, Eylau, &c. are numbered with surprises. Benningsen's
attack on Murat at Zarantin in 1812 was a true surprise, resulting from
the gross negligence and carelessness of the king of Naples.

An _order of battle_ is the particular disposition given to the troops
for a determined manoeuvre on the field of battle. A _line of battle_ is
the general name applied to troops drawn up in their usual order of
exercise, without any determined manoeuvre; it may apply to defensive
positions, or to offensive operations, where no definitive object has
been decided on. Military writers lay down twelve orders of battle,
viz.: 1st.