This is a 1914 Greece Red Cross surcharge, created during the Balkan Wars period by overprinting the earlier “Corinth Canal” definitive of 1901. The original 5 lepta green stamp is surcharged in red with “Κ.Π.” (for Κυβερνητική Προνοία / Government Aid) and a new value of 50 lepta to raise funds for wartime relief. The bold red overprint contrasts sharply against the detailed engraving of a ship passing through the Corinth Canal. Postally used examples like this one are especially desirable, as many surcharged issues were not widely circulated. A classic charity issue combining postal history, Greek overprints, and early 20th-century wartime philately.