Is this P.N. Blackstone that was later a prominent rancher in/around Muskogee? Cooper mentions him in his report of the Battle of Honey Springs:

Mr. P.N. Blackstone was particularly distinguished for his courage on the field. After being severely wounded, he succeeded in repulsing three of the enemy who attacked him, killing one and taking his gun, which he brought off with him, together with his own, closely pursued by the enemy, after the greater portion of our troops had left the field.

ORs Series 1, Vol 22, Part 1, Pg 461