Your probably referring to 29th Infantry. Company C was an element of the regiment's 1st Battlion; one of the battalion's three rifle companies. The regiment was assigned to 4th Infantry Division from 1933 until 1939, when the Army triangularized its infantry divisions (i. e., reduced the number of infantry regiments assigned to an infantry division from four to three). The regiment was a separate, non-divisional unit for the remainder of the war. In France, the regiment was assigned to Headquarters, Third Army and performed guard and security functions in rear areas. Campaign participation credits: Northern France, Rhineland, Ardennes-Alsace & Central Europe. How any of the above applies to your man depends on his dates of service with the regiment and other factors.
His service number, RA 13 393 126, is a little unusual. The Army initiated the use of two-letter prefixes (RA, ER, US, NG, etc.) in October 1945 but the policy wasn't fully implemented until much later.