In the Civil War, what was a "gray back"?

From the context, Allen is probably referring to lice.

"Grayback" may also have been slang for Confederate soldiers, even though outside the cavalry and officer's corps most of the uniforms being worn were butternut, which is a yellowish brown that looks grayish from a distance and was much more easily available as a uniform dye color.

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RE:

In the Civil War, what was a "gray back"?

It would seem like they would be Confederates, am I right? I just question it from this sentence:

"...all sorts of hats or caps; little to eat, but plenty of ammunition; dirty, ragged, and with a full assortment of 'gray backs." But we were veteran soldiers then."

-George H....

Gray Back

Greybacks were indeed Confederate soldiers, but they were usually the ones who first signed up at the start of the war, as they were able to afford the grey wool uniforms. (Most men who joined around 1863-1865 couldn't afford a uniform. They just wore regular clothes.)

A gray back is a confederate soldier. The southern soldiers mostly wore gray uniforms.

Greybacks were some of the original confederate soldiers who could afford the uniform they would receive after enlistment into the confederate army. They were named for the color of the uniform, grey.

Confederate soldiers or lice. Below is a link to other relevant slang of the period:

http://www.historum.com/showthread.php?t=813

You are right. He is saying that while the caps might have distinguished rank...officer from common soldier, they all wore the grey confederate uniform.

Yes they are confederates,their specialty is guerilla warfare tactics.

lice