Captain Ernest Robin of Orleans Guards Regiment, Louisiana Militia was captured at Shiloh on April 7, 1862 and taken to Camp Chase. He wrote three letters from Camp Chase that were never delivered. One to his father and one to his mother and one to his wife. All three letters were censored by Union authorities for containing hidden messages in salt water and not delivered. The letter to his father (H. Robin) was written between the lines of the letter in French and salt water was used. I am assuming that once heat was applied to the letter the hidden message would appear.

The source for this information came from "Letters of Governor Tod" "January 13, 1862 to January 11, 1864" located at the Ohio Historical Society in Columbus, Ohio. The cite of the first letter to his father was [756] and the letter to his mother was cited as [757] and the letter to his wife was cited as [758]

Captain Robin was not the only prisoner at Camp Chase to try and send hidden messages that were detected by Federal authorities.