In the affair at Valmy, at the battles of Jemmapes, Nordlingen, and Fleurus, the French had an artillery superior to that of the enemy, although they had often only two guns to one thousand men; but that was because their armies were very numerous.

It may happen that a general, more skilful in manoeuvring, more expert than his adversary, and commanding a better infantry, may obtain successes during a part of a campaign, although his artillery may be far inferior to that of his opponent; but on the critical day of a general engagement, his inferiority in point of metal will be severely felt." History furnishes us numerous examples of the use of artillery in protecting avenues of approach:--such as the defile of Koeesen at the battle of Auerstedt; the avenues between the redoubts of Pultowa, &c., &c.
When an army is forced to retreat, it covers its rear by that portion of its cavalry and mounted artillery which has suffered least during the battle.

By placing the squadrons of horse and the light batteries in echelon, the retiring column may be well protected.

The artillery, by using the prolonge, may also continue its retreat while in battery and firing.

It was in this way that at the battle of Albuera, in 1811, the French artillery on the left wing held in check the right and centre of the Anglo-Spaniards till the army effected its retreat; the artillery then retired in echelons, by batteries and fractions of batteries, under the protection of the cavalry.
We have already discussed, under the general head of tactics, the position and use of artillery on the battle-field a few additional remarks must suffice.
As a general rule, batteries should be placed in positions from which they can employ their fire to advantage, and also be free to move in any direction that the progress of the battle may require.