It is more correct to say that Indian Nations allied with the Confederacy could not be forced to operate outside their national boundaries without their consent. They gave their consent to go to Pea Ridge and elsewhere outside their national boundaries. The Choctaw did not see any action at Pea Ridge. Only the two Cherokee regiments were engaged at Leetown. The Choctaw distinguished themselves at Newtonia MO and elsewhere.

You might want to post your question on the Indian Territory message board at

http://history-sites.com/itcwmb