Emperor’s birthday
The emperor’s birthday was celebrated by the troops also during the war years. All contemporary reports and regimental histories mention this. It was a common custom. Franz Joseph’s birthday was August 8. So, based on the dating, the presented badge was made for the emperor’s 85th birthday in 1915.
I tried to find a suitable photo or card for the badge. The closest match is a birthday a year later (the last), which was held in Cetinje, the capital of occupied Montenegro, with the parade shown in the picture. I would say that such a badge could have been given to the honor guard, but I don’t know if a celebratory badge was made in 1916. I also don’t know how widely the badge was distributed? Since the occasion was celebrated by all the troops, I assume that it was a centrally ordered and distributed badge. This is somewhat contradicted by the fact that I have not seen any other one besides the piece in question, so it cannot be very common.