A very nice and original Austro-Hungarian Army christmas cap badge commemorating the "3. Weihnachten im Feld, 1916" or 3rd Christmas in Field, 1916. Working pin and catch on the reverse, nicely marked for "KuK Kriegsfürsorgeamt Vienna."
 
When the appearance of the Austro-Hungarian army changed in 1908 after the color "pike gray" was introduced to the infantry, the colorful uniforms and headgear fell victim to standardization, making it more difficult to recognize the individual regiments. Eventually, soldiers would decorate their caps with badges that identified their corps, division, brigade, regiment, or battalion. 
 
As the popularity of cap badges grew, it was followed by badges for Christmas, battles, disdain for the enemy, etc. Many of the badges known today were rather unofficially created and issued. The war ministry tried to put a stop to this trend and forbade wearing an unofficial cap badge in the ordinance of the kuk war ministry dated October 28, 1918.