Sounds like a worthy project. Ga. is the old abbreviation for Georgia, just as N.C. stands for North Carolina.

You asked for help with this --

"1st Ga. Reg. 2nd Cavalry Gen. Dange's Brigade, C. Co. N.C. Volunteers."

Here's the problem: there are references to three and possibly four different military commands here.

1) "1st Ga. Reg." means 1st Georgia Regiment. There's no reference to a company, which may or may not be important. However, since at least three different infantry commands from Georgia carried the designation "1st Georgia", we don't know which is meant.

2) "2nd Cavalry" means what it says, but we don't know what state. We might also need to know if this means 2nd (State) Cavalry Regiment or 2nd (State) Cavalry Battalion.

3) "C. Co. N.C. Volunteers." Means Co. "C", North Carolina Volunteers. Many wartime documents use the word "volunteers" when what's meant is infantry regiment. However, we have another missing element, which is the regimental designation, such as 1st or 2nd.

4) "Gen. Dange's Brigade" may mean Brig. Gen. Junius Daniel's Brigade, composed of several regiments and a battalion from North Carolina.

Looks as if you're reading from a hand-written document, and certain elements were faded or unclear and left out of your document.