Gustavus Adolphus of Sweden not only improved the character of artillery, but also gave to it great development as an arm of service.  At the battle of Breetenfield he had one hundred pieces of artillery, great and small, and at the camp of Nuremberg he numbered about three hundred.  This king also made a more skilful use of his cannon by uniting them more in mass than had been done by his predecessors; his system was nevertheless very imperfect.  In the disposition of this arm on the field of battle, a vast improvement was made by Conde, Turenne, and Prince Eugene of Savoy.  Frederick the Great also made great use of this arm, and was the first to introduce horse artillery.  This mode of using field-pieces has peculiar properties which in many circumstances render it an invaluable arm.  The promptness and rapidity of its movements enable it to act with other troops without embarrassing them.  The French soon introduced into their army the improvements made by the king of Prussia, and in 1763 the celebrated Gribeauval appeared.  He improved the form of the cannon and greatly diminished the weight of field artillery, giving it an organization which has been but slightly changed since his time.

The successive improvements in artillery have for a long time constituted a prominent feature in war.  The power of this arm to throw projectiles to a great distance, and to overturn and destroy opposing obstacles, renders it a necessary arm on the battle-field, and a strong barrier and safeguard of states.  It is an essential element in all army organization.

In our army we have four regiments of artillery, forming the basis of forty batteries.  In the French service there are fourteen regiments, forming the basis of two hundred and six field batteries.

The term battery, when applied to artillery as an arm of service, refers to a permanent organization of a certain number of cannon, with the men and other accessaries required to serve them.  This is the unit of force in this arm.  The regimental organization is a mere nominal arrangement, for in actual service artillery acts by batteries, and never by regiments.  Its strength is therefore invariably estimated by the number of its batteries.

A battery is ordinarily composed of six pieces, two of them being howitzers.  The lighter batteries would, in our service, be formed of six-pounder guns and twelve-pounder howitzers; and the heavier of twelve-pounder guns and twenty-four-pounder howitzers.  These heavy batteries would usually form the reserve.  Each piece being attended by its caisson, this formation would give twelve carriages to each battery, six for the guns and six for the caissons.  The extra caissons form a part of the reserve, and move with the train.  In some foreign services a battery is composed of eight pieces with their caissons.

This arm admits of three formations—­in column, in battle, and in battery.  In column it ordinarily moves by sections of two pieces, each piece being followed or preceded by its caisson.  Columns of half-batteries are sometimes formed, and also columns of single pieces; but the latter ought never to be employed except in cases of necessity in passing a narrow defile, and at a distance from the enemy.