I received the image above from a party who was interested in finding out more about this piece, with the following information: "Attached is a photograph of a piece of pottery that I found on the Somme battlefield, it shows a partial crest on it and I'm trying to identify if this was a family crest or a manufacturers emblem."
I suspect that this is a French shard and eventually found information about faiences made in Longwy .The French ebay site shows plenty of pieces by this manufacturer and one included the same mark.
The company was founded in 1798 and is famous for the production of
émail cloisonné (introduced by Amédée de Caranza in 1875), see: INFO FAIENCE
and a good website with many marks