This 5 heller green stamp was issued in 1917 for the Austro-Hungarian Military Post (K.u.K. Militärpost) in Bosnia & Herzegovina during World War I. It features a finely engraved portrait of Emperor Karl I, the last ruler of the Austro-Hungarian Empire, set within a bold ornamental frame typical of wartime issues. Produced during the empire’s final turbulent years, the stamp reflects the administrative control exercised through military postal services in occupied territories. Clean lines, crisp typography, and the distinctive “BOSNIEN-HERCEGOVINA” inscription make it a popular addition for collectors of imperial, WWI, and Balkan postal history.