proceededandits flexibility—the way in which the corps kept changing roles with
each other as operations unfolded. So important was this aspect of the matter
that, in time, it became standard practice to judge the military power of a country
by the number of corps it could field.
Now a corps acted as a vanguard, now as a pivot. Now it served as a flank guard
in relation to the army as a whole, now as a rearguard. A corps might very well
find itself acting as a hammer on one day, then serving as the anvil on the next.
War itself became a question of managing time and space; as the Confederate
commander Nathan Bedford allegedly put it at a later time, succinctly but not at
all inaccurately, one had to ‘gitting tha fustest with the mostest’. All this pre-
supposed very good staff work and traffic control, or else the endless columns of
marching men and the trains of guns and carriages that followed them would
quickly become hopelessly entangled. It is a tribute to theGrande Arme ́e, and to
the new system of operational warfare that it invented and waged, that this
control and this staff work were usually, though not invariably, achieved.
To illustrate how things worked out in practice, take the movements of the 7th
Corps. Commanded by Marshal Joachim Murat, the emperor’s brother-in-law, it
differed from the rest in that it was made up mainly of cavalry. Originally, as the
only one of the corps stationed south of Strasbourg, its role was to mount a
demonstration in the Black Forest region. After all, as Freiburg’sAlte Franzosen-
wegreminds visitors to this day, for centuries this had been the route that French
armies took on their way to invade southern Germany. The trick worked, helping
to explain why the Austrians remained at Ulm as if mesmerized, allowing
themselves to be surrounded by the rest of theGrande Arme ́ewhich was marching
further to the north. Later, the corps started advancing east along the Danube
Valley so as to form the anvil against which the Austrians at Ulm were pressed.
Later, its mission was changed again. Now, it formed the vanguard, marching
straight eastward along the Danube Valley until it reached, and entered, Vienna.
Or take the 3rd Corps. Its commander was Marshal Louis Nicolas Davout, who
was probably the most capable of all Napoleon’s subordinates and the only one
whose grasp of operational warfare rivalled the emperor’s own. During the first
stage of the campaign, the one that culminated in Ulm, it joined the 2nd Corps in
providing cover to theGrande Arme ́e’s exposed northern flank against possible
Prussian intervention. At Ulm itself, it formed the outer (easternmost) part of the
ring that closed on ‘the unfortunate General Mack’. Meanwhile, the 2nd Corps,
having parted company with it, had gone to Munich, seventy-five miles to the east
as the crow flies. There, its task was to wait for, and if necessary halt, an anticipated
attack by Austria’s Russian allies. Next, during the advance along the Danube
towards Vienna, the 3rd Corps found itself in the vanguard directly behind Murat.
Having followed the latter into the Austrian capital, it was left to garrison the city
but did not remain there for long. On the night of 30 November–1 December, an
imperial summons arrived, sending it on a thirty-six-hour, sixty-mile, march to
Austerlitz, where it did, in fact, arrive in time to play a critical part in the battle.
Acting on the defence, a corps that ran into the enemy might call for assistance
and hold out until it arrived. Acting on the offence, it could tie down the enemy
22 The Evolution of Operational Art