In Naples and Napoleon John Davis takes the southern Italian Kingdom of the Two Sicilies as the vantage point for a sweeping reconsideration of Italy's history in the age of Napoleon and the European revolutions. The book's central themes are posed by the period of French rule from 1806 to 1815, when southern Italy was the Mediterranean frontier of Napoleon's continental empire. The tensions between Naples and Paris made this an important chapter in the history of that empire and revealed the deeper contradictions on which it was founded. But the brief interlude of Napoleonic rule later came to be seen as the critical moment when a modernizing North finally parted company from a backward South. Although these arguments still shape the ways in which Italian history is written, in most parts of the North political and economic change before Unification was slow and gradual; whereas in the South it came sooner and in more disruptive forms.

Davis develops a wide-ranging critical reassessment of the dynamics of political change in the century before Unification. His starting point is the crisis that overwhelmed the Italian states at the end of the 18th century, when Italian rulers saw the political and economic fabric of the Ancien Régime undermined throughout Europe. In the South the crisis was especially far reaching and this, Davis argues, was the reason why in the following decade the South became the theatre for one of the most ambitious reform projects in Napoleonic Europe. The transition was precarious and insecure, but also mobilized political projects and forms of collective action that had no counterparts elsewhere in Italy before 1848, illustrating the similar nature of the political challenges facing all the pre-Unification states.
Although Unification finally brought Italy's insecure dynastic principalities to an end, it offered no remedies to the insecurities that from much earlier had made the South especially vulnerable to the challenges of the new age: which was why the South would become a problem - Italy's 'Southern Problem'.