King Ferdinando II of the Two-Sicilies, part of the Spanish Royal Family, annoyed the British by siding with Don Carlos. They were also concerned by the growing discontent in the Two-Sicilies and the increasing support for a republican revolution. Why were the British or French concerned at all? What was Sicily to them? The answer, of course, was that Sicily was right next to the British naval bastion of Malta and straddled the main seaway to the Suez Canal which was just starting to be built the year before Garibaldi and his men landed at Marsala. The French and British were therefore greatly concerned about any unrest that might disturb this enterprise upon which so much of global commerce was to depend. The British even sent warships to encourage the Neapolitan navy to stay away while Garibaldi and his men were landing (once the troops had disembarked the Neapolitans destroyed one ship and captured the other).
Garibaldi captured Palermo and his ranks slowly grew as locals volunteered to join him. The Neapolitan army also had a problem with desertion. A key element was the local aristocracy who responded in various ways to the crisis, none of them very helpful to Francesco II. Some fled the island immediately as soon as Garibaldi landed and these were those most supportive of the Bourbon monarchy. Obviously, they would be no help. Most, however, considered the cause of Francesco II lost and decided to make common cause with Garibaldi who promised to respect their rights and privileges. This would later cause a degree of rebellion and banditry by those peasants who felt Garibaldi had sold them out by not tearing down the aristocracy completely and redistributing their lands. King Ferdinando II had shown that he would do whatever was necessary to maintain his rule, be it promising a constitution only to revoke it later or shooting down rebels and shelling entire cities to rubble. If he had still been around things might have been different but few had confidence that Francesco II was made of such tough stuff. The pragmatic types looked at the situation and reasoned that the Bourbons were doomed and their only options for the future would be a united Italy ruled by Giuseppe Mazzini and his radical republicans or a constitutional monarchy ruled by King Vittorio Emanuele II. Mazzini was unthinkable so these invariably suppressed their distaste for Garibaldi and supported his red shirt army to maintain the existing social order.
In a last, desperate effort to avoid disaster and win back popular support, King Francesco II issued a constitution in June but it was to no avail. After the “now you see it, now you don’t” constitutions of his father, very few people were prepared to believe that the King was serious about constitutional government and simply ignored him. More volunteers joined Garibaldi though the Neapolitan army still had some sizeable garrisons on the island. In July Garibaldi captured Milazzo with 5,000 men after the overall Neapolitan commander refused to reinforce the garrison there. His caution did him no good and a few days later he surrendered Messina to Garibaldi by which time it was the rebels who held a significant numerical advantage and the remaining garrisons surrendered quickly. Throwing caution to the wind (and alarming the government in Turin) Garibaldi wasted no time and transferred his forces over to the mainland at Calabria. After that, a string of victories ensued as many Neapolitan forces deserted, some even joining the red shirts and most of those who did offer resistance did so with little support or coordination. The army and navy seemed to melt away, King Francesco II fled Naples and made his last stand at Gaeta.