The first official use of Shiloh as the name for the battle comes in the official report of Col. Eli S. Shorter, 18th Alabama Infantry. The report is dated April 9, 1862 and refers to "the great historic battle at Shiloh Church." OR vol. 10, part 1, page 557.
The first to use the term "Battle of Shiloh" was Lt. Col. O.F. Strahl, 4th Tennessee Infantry who refers to the "battle of Shiloh" in his report dated April 10, 1862. OR vol. 10, part 1, page 431.
The first general officer to use the name in an official document appears to be Brig. Gen. Sterling A.M. Wood, who reports on the activities of his brigade, in his report dated April 15, 1862.OR vol. 10, part 1, page 590.