What was the SCA?

[Christine]

I'm talking about a Civil War term. I found a note on fold3:

"Mrs Noland dress maker on C between 41/2 & 6th St came to the Provost Marshals office with F A Aiken – endeavoring to obtain pass.

This man Aiken has been pointed out to us as one of the SCA.

RHD knows her."

So, I'm wondering what the SCA was then. The date on the note was August 28, no year.