First World War WW1 Trench Art or POW Art.  Features the Imperial German belt buckle crest in the centre and the names of 4 earlier Western Front battles.  Yser, Verdun, Somme & Marne. 

From some quick research, it appears only the Germans and the French participated in all four of those battles, so it's quite possible this brass ashtray was made by or for, a German or French soldier as POW art or as a trench art souvenir.  There is no history attached so this is just my amateur assessment of the artifact. 

***I am always on the look out for collectibles (any era) to the Princess Louise Dragoon Guards for trade or purchase.***