This rule is almost universal in Europe.

The number of marshals in France under Napoleon was so great, that officers of this grade were often assigned to _corps d'armee_.
A grand division of an army should be commanded by a _General of Division_.

In England, the assimilated grade is that of major-general, and in France at the present time, the younger lieutenant-generals, or the _marechaux-de-camp_, command divisions.
A brigade should be commanded by a _Brigadier-general_.

At the present time in the French service, _marechaux-de-camp_ act as commanders of brigades.
The several _corps d'armee_ are designated by numbers, 1st, 2d, 3d, &c., and in the same way the several divisions in each _corps d'armee_, and the several brigades in each division.
When the number of troops are placed on a war footing, each _corps d'armee_ ordinarily contains from twenty to thirty thousand men.
The command of these several _corps d'armee_, divisions, and brigades, is taken by the officers of the corresponding grades according to seniority of rank, and without reference to arms, unless otherwise directed by the generalissimo, who should always have the power to designate officers for special commands.
The _chief of staff_ of an army is usually selected from the grade next below that of the general commanding, and receives the title, for the time being, which is used to designate this special rank.

In some European armies, and formerly in our own service, this officer was called major-general.