At the start of the level, head left into the bunker and keep going left to find this item.
"Tobacco case made from shell casing. Empty munitions were often recycled. Some exploded shell materials were already aesthetically interesting, otherwise soldiers would rework their finds to create handy items. Tobacco was precious so soldiers were eager to keep it dry. Many accounts from the trenches express soldiers' appreciation of the Christmas cigar, a special festive treat for the troops."