Funny story. I remember the story I think related in Ken Burns' "The Civil War" classic. Hardtack was stamped with the letters BC which stood for Brigade Commissary but the men said it stood for Before Christ.
http://civilwartalk.com/threads/wormy-hardtack.78815/

……

“One day a lot of boxes, of peculiarly hard crackers, arrived in the camp of the Vth Excelsior. Several of the boys wondering at the meaning of the brand upon the boxes, which was as follows:

‘B. C.
603.’

“Various interpretations were given, but all were rejected, until one individual declared it was all plain enough_couldn’t be misunderstood.

“ ‘Why, how so?’ was the query.

“ ‘Oh!’ he replied, ‘that is the date when the crackers were made__six hundred and three years before Christ__(603 B. C.)’ “

The United States Service Magazine, Volume 3, p. 21

https://books.google.com/books?id=rusRAAAAYAAJ&pg=PA21&lpg=PA21&dq=Hardtack++B.+C.&source=bl&ots=RFvv4Sipls&sig=N7EfXkJX7NKpzu4F1Xueq961LW8&hl=en&sa=X&ei=bBbqVNvdMZHZoAS55IDADg&ved=0CDoQ6AEwAw#v=onepage&q=Hardtack%20%20B.%20C.&f=false