it has been given them in the
volunteer organization, or pertains to them in the line of the regular
or volunteer army. All the department officers (meaning all except
aides) have a number of assistants, and the general officers have staffs
and aides of their own, to which they are entitled by law. The total
number of officers on duty at the headquarters may amount to fifty or
more, and there is plenty of work for all of them during a campaign.
Besides the regular staff, constituted as above related, there are the
officers of an infantry regiment which furnishes guards and escorts, and
officers of cavalry squadrons detailed to furnish orderlies. The
headquarters of the army is therefore a town of considerable population.

At the headquarters of the different corps the staffs are as follows:

_An Assistant Adjutant-General_--Lieutenant-colonel.
_A Chief Quartermaster_--Lieutenant-colonel.
_A Chief Commissary_--Lieutenant-colonel.
_An Assistant Inspector-General_--Lieutenant-colonel.

[These officers derive their rank from their position, under a law of
Congress.]

_A Medical Director_--being detailed from
the senior surgeons of the regular or
Volunteer army, and ranking as a
major.

_A Commissary of Musters._
_A Provost Marshal._
_A Signal Officer._

[These officers are detailed from the line, and have the ranks which
there belongs to them. The signal corps is, however, now being
organized, with ranks prescribed by law.]

_Aides-de-Camp_--one with the rank of major, and two with the rank of
captain. Besides these, additional aides are sent to the corps from
those created under an act of Congress of 1861--now repealed--and are
detailed from the line.

* * * * *

The quartermaster, commissary, and medical director generally have
assistant officers. There is a squadron of cavalry and usually a company
of infantry at each corps headquarters.

The staffs of divisions and brigades resemble those of the corps, except
that the regular staff officers usually rank only as captains, except in
cases where a major-general commands; he is entitled to an assistant
adjutant-general with the rank of major. Officers detailed from the line
to act on any staff in any capacity, bring with them the rank they hold
in the line. They are not entitled, except the authorized aides and in
some other particular cases, when ordered by the War Department, to
additional allowances; bu