The Neapolitan Republic was a republic created in Naples, which lasted from 22 October 1647 to 5 April 1648. It began after the successful revolt led by Masaniello and Giulio Genoino against King Philip III and his viceroys.

The leader of the Republic was Henry II of Lorraine, duke of Guise, descendant of the former king of Naples Rene I of Anjou.

The Republic had the following official names: Serenissima Repubblica di questo regno di Napoli ("Most Serene Republic of this Kingdom of Naples"), Reale Repubblica ("Royal Republic"), and Serenissima Monarchia repubblicana di Napoli ("Most Serene Republican Monarchy of Naples"). All indicated the double nature of the Republic, both republican and monarchical, and "Serenissima" was a purposeful comparison with the famous Italian maritime republic with the same title, Venice. The coat of arms was a red shield with the motto S.P.Q.N. (i.e., Senatus Populusque Neapolitanus), in imitation of the well-known S.P.Q.R., the initialism of the Latin phrase, Senatus Populusque Romanus ("The Senate and the People of Rome"), Thus, the Neapolitan phrase meant "The Senate and People of Naples." The coat of arms contained the crest of the duke of Guise.

The Kingdom of Naples had been in personal union with the crown of Spain since 1504. In the first half of the 17th century Naples was in the midst of a harsh economic crisis, one which was affecting all of Europe. In Naples it was worsened by a viceregal government with few local concerns, interested only in helping to finance the series of continent wide wars in which Spain had become entangled.

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