In the Saddle by Oliver Optic

The Texan Rangers were formed in a rather compact mass, while the Union line was considerably extended. Captain Truman had ideas of his own; and, though he was not a martinet, he was disposed to follow strictly the rules and precedents of military practice. His men could not very well fire into forty-five men huddled together in a small space without hitting some of them. On the other hand, the enemy might discharge a volley into his force, placed about six feet apart, with comparatively little effect.

He was surprised to observe how few of the Rangers fell from their horses at the first discharge of his men; but their practice immediately began to improve, and as soon as the detachment of Lieutenant Gadbury dashed into the road in the rear of the enemy, the fire became very destructive. Many of the enemy were killed and wounded, and it looked as though they would all be destroyed.