After 1650 or so, when things became more institutionalized, each unit formed
part of its respective arm. Each came under its own commander who was himself
commissioned into the arm in question. There, things rested until the eve of
battle itself. At that point, the commander-in-chief worked out theordre de
battaileand assembled his subordinates to explain it to them. A ‘general’—
meaning, originally, an officer senior enough not to be tied to one arm only—
would be put in charge of units of different kinds constituting the right wing, the
left wing, the reserve, and so on. However, the commands in question were not
intended to be permanent. When the battle was over, they were dissolved almost
immediately so that things reverted to their normal state.
The Marshal de Saxe in hisReveries on the Art of War, which were written in
1732, played with the idea of re-establishing ‘legions’ more or less on the Roman
model. Each one was to be ‘furnished with everything that can be required to
fortify itself’, and each one was to come with its own permanent commander and
headquarters as a way to facilitate command and control. Hence, ‘if the com-
mander in chief...wants to occupy a post, to obstruct the enemy in their
projects, or in a hundred different situations which are found in war, he has
only to order a particular legion to march’. 24 However, nothing seems to have
come out of it. In any case, Saxe’s work remained unpublished for twenty-five
years after his death, when it was rescued from oblivion.
Apparently, the first to experiment with permanent formations combining the
various arms was the Duc de Broglie during the Seven Years War in Germany. Yet,
the real changes in organization that opened the door to operational warfare, as it
were, were only made by the National Assembly in 1794. Even so, they remained
incomplete. Here, we shall not trace developments in detail, and, indeed, this is a
field on which much research remains to be done. Suffice it to say that, in 1805,
the first consul, as Napoleon then was, was experimenting with them; 25 five years
later, the system had reached maturity.
At the heart of the new system stood thecorps d’arme ́e, a permanent formation
made up of all three arms: that is, infantry, cavalry, and artillery. It was provided with
its own engineering service, intelligence service (each marshal, or corps commander,
had at his disposal a fund on which he could draw to engage spies), medical service,
and, of course, headquarters. That headquarters, in turn, came complete with the
necessary staff officers, secretarial personnel, messengers (everything still depended
on messengers, who were always in short supply; as a result, commanders often
‘borrowed’ each other’s messengers), and the like. Depending on the number of
divisions it contained—the divisions themselves were miniature corps—normally
each corps was 20,000 to 30,000 men strong. Here and there, even larger ones,
comprising as many as 40,000 men, were created. Simply by adding or detaching
divisions, the corps could be adapted to the mission at hand.
Perhaps most important of all, the corps were roughlyinterchangeable. As a result,
they were able to step into each other’s shoes without any need for changes in
organization. Previously, waging combined-arms warfare meant that units of each
arm had to be carefully pre-positioned before, besides, and behind each other, so
they could play their allocated role in the commander’s plan. An excellent example is
20 The Evolution of Operational Art