In the 1848-1867 period, the Habsburg Adriatic was contended by incipient nationalisms, particularly the Italian, German, and South Slavic. The Fight for a Supranational World focuses on Trieste, Fiume/Rijeka, and Dalmatia, where opposing nationalisms found themselves at grips with centuries-long traditions of municipal autonomy, dynastic loyalty, regional patriotism, and ethnic hybridity—all qualities enshrined within Habsburg supranationalism. There were attempts by nationalist activists to exploit ethnic and linguistic elements to form or join national states, but these largely failed until much later in the century.

Contrary to the current consensus within nationalism scholarship, which is steeped in the notion of "liberal nationalism," The Fight for a Supranational World argues that in 1848 and the following years, nationalism was illiberal due to its exclusionary or assimilatory tendencies in its quest for cultural and linguistic homogeneity. This work also shows how Habsburg supranationalism, neglected within nationalism studies and political science more broadly, needs to be the bedrock for more accurate theorizations of nationalism that would prove the relevance of Elie Kedourie's and Eugen Weber's works, among others, despite Ernest Gellner's and Benedict Anderson's enduring popularity.