Such was the case with Napoleon at Wagram.

In Saxony, in 1813, he was several times obliged to substitute his artillery to supply the want of other arms.
In the defence and attack of field-works, and in the passage of rivers, artillery plays an important and indispensable part; but it here becomes an auxiliary to the dispositions of the engineers, or at least acts in concert with that arm.
The troops of artillery, in all well-regulated army organizations, should equal about two-thirds of the cavalry, or one-seventh of the infantry.[36] [Footnote 36: To qualify himself for the duties connected with his arm of service, the artillery officer must make himself thoroughly acquainted with--.
_The Instruction for United States Field Artillery, horse and foot; Capt.

Anderson's Instruction for Garrison Artillery; Kinsley's Notes on Pyrotechny; Knowlton's Notes on Gunpowder_,&c.; and The writings of Thiroux and Piobert on theoretical and practical instruction, and the writings of Jomini, Decker, and Okotmeff, on the use of this arm on the field of battle.
The following list of books of reference may be of use to those who wish to make themselves perfectly familiar with all the branches of artillery.
_Histoire general de l'artillerie_.

Brunet.
_L'artillerie a cheval dans les combats de cavalerie_.

Par un officier de l'artillerie Prussienne.
_Considerations et experiences sur le tir des obus a bulles_.