Beautifully decorated, a work of art, the photo's really don't do justice to them. Appears to be French, stamped "REMANIE" which indicates that the casing had been re-used. Remanié means refurbished, recast, refilled perhaps, presumable meaning a shell case that is on its second time or third time around.

One dated 9.1.18, other 10.1.18, made by Atelier de Constructions de Rennes, France, made Sept. 1917. 

Height 35 cm width at top 10 ½ cm weight 2386g

In good condition, both have small splits at top, please see photo's