Austro-Hungarian Army of the Isonzo Front veteran's badge from 1915.

These were unofficial commemorative badges, often worn on a field cap.
The badge was dedicated to the men who fought at the Isonzo Front in Italy in 1915. The Battles of the Isonzo were a series of 12 between the Austro-Hungarian and Italian armies in the First World War, mostly on the territory of present-day Slovenia, and the remainder in Italy along the Isonzo River on the eastern sector of the Italian Front, between June 1915 and November 1917.