At various times and places Confederate soldiers were issued "hickory shirts."  The time preceeding the Battle of Franklin is one of those times.  Hickory shirts were made from heavy twilled cotton canvas, usually with a narrow blue and white stripe pattern, and were a common workman's shirt in the mid 19th century (so they are appropriate for lots of impressions).  The hickory shirts for Franklin will be available in size regular (up to a 42) or large (up to a 48).