in Genoa planning an expedition against Sicily and Naples, with the covert support of the United Kingdom. Lorenzo del Boca suggested that British support for Garibaldi's expedition was spurred by the necessity to obtain more favourable economic conditions for Sicilian sulfur, which was needed in great quantities for munitions. Search for a casus belli The Kingdom of Sardinia-Piedmont needed a presentable casus belli in order to attack the Kingdom of the Two Sicilies. This was needed for the House of Savoy, which however never gave any declaration of war against the Bourbon kingdom, a necessary condition, since this was among the requirements presented to Cavour. The only occurrence that would have satisfied this requirement was an uprising from within. Such an event would have felt the alienation of the people to the dynasty that ruled in Naples and, particularly, the inability of Francis of Bourbon, to ensure, in forms acceptable public policy in their domains. Sicily, as shown by the history of the past decades, was fertile ground, and the liberal south, especially those returning after an amnesty granted by the young King, who worked in this direction for some time. The expedition The Red Shirts In March 1860, exile Rosolino Pilo exhorted Giuseppe Garibaldi to take charge of an expedition to liberate southern Italy from Bourbon rule. Garibaldi was against it at first, but eventually agreed. By May 1860, Garibaldi had collected 1,089 volunteers for his expedition to Sicily. A total of 336 volunteers came from the contemporary Italian regions, including Genoa (156 volunteers), Tuscany (78 volunteers), Sicily (45 volunteers) and Naples (46 volunteers), with only 11 from Rome and the Papal States. The largest number of volunteers came from Austrian Lombardy and Venetia, with 434 from Lombardy and 194 from Venetia. An additional 33 foreign volunteers joined the expedition. This included 14 ethnic Italians from the Trentino region of Austria, as well as István Türr and three other Hungarians. The volunteers came from middle-class backgrounds, with the vast majority being students and skilled craftsmen. The 1,089 volunteers were unfavourably armed with obsolete muskets, and wore red shirts and grey trousers as their uniform. During the night of 5 May, a small group led by Nino Bixio "seized" two steamships in Genoa from the Rubattino shipping company. (The ships were actually secretly provided by Rubattino.) The two ships were renamed Il Piemonte and Il Lombardo. At nearby Quarto dei