A corruption of TomMASo ANIELLO, a Neapolitan fisherman, who led the revolt of July, 1647. The great grievance was a new tax upon fruit, and the immediate cause of Masaniello's interference was the seizure of his wife (or deaf and dumb sister) for having in her possession some contraband flour. Having surrounded himself with 150,000 men, women, and boys, he was elected chief of Naples, and for nine days ruled with absolute control. The Spanish viceroy flattered him, and this so turned his head that he acted like a maniac. The people betrayed him, he was shot, and his body flung into a ditch, but next day it was interred with a pomp and ceremony never equalled in Naples (1647).
Auber has an opera on this subject called La Muctte de Portici (1828).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894