This is the Duchy of Braunschweig’s 1914 War Service Cross for Combatants, the Duchy’s equivalent to the 1914 Iron Cross 2nd Class. The Duchy of Braunschweig had been the Kingdom of Hannover’s vassal state. Both Hannover and Braunschweig were absorbed into Prussia at the 1866 Austro-Prussian War’s conclusion, which effectively concluded Germany’s unification struggles. Prussia had emerged as the dominant power within Germany and went on to lead the country’s combined forces to victory over France in the 1870-1871 Franco-Prussian War. The German Empire was created 1871 and Prussia’s König Wilhelm I became Imperial Germany’s Kaiser Wilhelm I.
The War Service Cross in the 1st and 2nd Classes was only awarded during and after WW I to Germans, particularly those from Braunschweig. It would make a fine addition to your collection.