At Mansfield, where Fields was killed, Allen's was on the Confederate right while Fields and the Crescent were on the far left. Because the different units converged in a bottleneck it is possible that, if (Martin/McDonald) was in the 17th at this time, he could still have come upon Fields.
You said that this was all the information that you had. I am very interested in his possible connection with the Crescent; do you have any documentation showing his service with them? Any photos?
Clay Lord
crescentregiment@comcast.net