On the entry of the French into Naples and the establishment of the Parthenopaean Republic (1799) he adhered to the new government, and when the Bourbon king Ferdinand IV reconquered the city Colletta was thrown into prison and only escaped the death penalty by means of judiciously administered bribes. Turned out of the army he became a civil engineer, but when the Bourbons were expelled a second time in 1806 and Joseph Bonaparte seized the throne of Naples, he was reinstated in his rank and served in the expedition against the brigands and rebels of Calabria.
In 1812 he was promoted general, and made director of roads and bridges. He served under Joachim Murat and fought the Austrians on the Panaro in 1815. On the restoration of Ferdinand Colletta was permitted to retain his rank in the army, and given command of the Salerno division. At the outbreak of the revolution of 1820 the king called him to his councils, and when the constitution had been granted Colletta was sent to put down the separatist rising in Sicily, which he did with great severity.
He fought in the constitutionalist army against the Austrians at Rieti (March 7, 1821), and on the re-establishment of autocracy he was arrested and imprisoned for three months by order of the prince of Canosa, the chief of police, his particular enemy. He would have been executed had not the Austrians intervened in his favour, and he was exiled instead to Brno in Moravia; in 1823 he was permitted to settle in Florence, where he spent the rest of his days engaged on his Storia del reame di Napoli.
His history (1st ed., Capolago, 1834), which deals with the reigns of Charles III and Ferdinand IV (1734-1825), is still the standard work for that period; but its value is somewhat diminished by the authors bitterness against his opponents and the fact that he does not give chapter and verse for his statements, many of which are based on his recollection of documents seen, but not available at the time of writing. Still, having been an actor in many of the events recorded, he is on the whole accurate and trustworthy.
See Gino Capponi's memoir of him published in the Storia del reame di Napoli (2nd ed., Florence, 1848).
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