The legend dates this to at least after fall 1914 when German forces were checked near Ypres in Belgium.
From eBay; sepia tone removed and seller's mark removed by gogm using Photoshop.
Elisabeth wears a late pre-war-style dress with a stripe-like band across mid-bodice in this celebratory image.
Keywords: Queen Elisabeth of Belgium, Wittelsbach family, Wettin family, Princess, Queen, bouffant coiffure, high enclosing neckline, natural waistline, tight skirt, choker necklace, necklace