The paper discusses how the 1912 Italian annexation of the Dodecanes unsettled the international sphere and shaped international heritage politics lastingly. The Islands Hospitaller buildings were important for policies of Italianisation and accelerated the nationalisation of crusader sites elsewhere. Various European powers and transnational bodies, including the different successor organisations of the Knights Hospitaller became involved in a ‘heritage’ arms race during the interwar years, but the sites also played an important role in anti-colonial movements across the Mediterranean. As such they offer a prism to compare and link the uses of heritage across different regimes from the eve of the first world war to the end of the second and assess their legacies in the present.