a wrought-copper tube
screwed into a chambered brass breech, bound with four iron hoops. The
copper tube was covered with layers of mastic, wrapped firmly with
cords, then coated with an equalizing layer of plaster. A cover of
leather, boiled and varnished, completed the gun. Naturally, the piece
could withstand only a small charge, but it was highly mobile.

Gustavus abandoned the leather gun, however, in favor of a cast-iron
4-pounder and a 9-pounder demiculverin produced by his bright young
artillery chief, Lennart Torstensson. The demiculverin was classed as
the "feildpeece" _par excellence_, while the 4-pounder was so light
(about 500 pounds) that two horses could pull it in the field.

These pieces could be served by three men. Combining the powder charge
and projectile into a single cartridge did away with the old method
of ladling the powder into the gun and increased the rapidity of
fire. Whereas in the past one cannon for each thousand infantrymen had
been standard, Gustavus brought the ratio up to six cannon, and
attached a pair of light pieces to each regiment as "battalion guns."
At the same time he knew the value of fire concentration, and he
frequently massed guns in strong batteries. His plans called for
smashing hostile infantry formations with artillery fire, while
neutralizing the ponderous, immobile enemy guns with a whirlwind
cavalry charge. The ideas were sound. Gustavus smashed the Spanish
Squares at Breitenfeld in 1631.

[Illustration: Figure 6--LIGHT ARTILLERY OF GUSTAVUS ADOLPHUS (1630).]

Following the Swedish lead, all nations modified their artillery.
Leadership fell alternately to the Germans, the French, and the
Austrians. The mystery of artillery began to disappear, and gunners
became professional soldiers. Bronze came to be the favorite gunmetal.

Louis XIV of France seems to have been the first to give permanent
organization to the artillery. He raised a regiment of artillerymen in
1671 and established schools of instruction. The "standing army"
principle that began about 1500 was by now in general use, and small
armies of highly trained professional soldiers formed a class distinct
from the rest of the population. As artillery became an organized arm
of the military, expensive personnel and equipment had to be
maintained even in peacetime. Still, some necessary changes were slow
in coming. French artillery officers did not receive military rank
until 1732, and in some countries d