at Ostia. At this same time (846) the episcopal see of Gaeta was founded when Constantine, Bishop of Formiae, fled thither and established his residence. He was associated with his son Marinus I. They were probably violently overthrown (they disappear suddenly from history) in 866 or 867 by Docibilis I, who, looking rather to local safety, entered into treaties with the Saracens and abandoned friendly relations with the papacy. Nevertheless, he greatly expanded the duchy and began construction of the palace. Greatest of the hypati was possibly John I, who helped crush the Saracens at Garigliano in 915 and gained the title of patricius from the Byzantine Emperor Constantine VII.
The principle of co-regency governed the early dynasties: Docibilis associated John with him and John in turn associated his son Docibilis II with him. In 933, three generations were briefly co-ruling: John I, Docibilis II, and John II. On the death of Docibilis II (954), who first took the title dux, the duchy passed from its golden age and entered a decline marked by a division of territory. John II ruled Gaeta and his brother, Marinus, ruled Fondi with the equivalent title of duke. Outlying lands and castles were given away to younger sons and thus the family of the Docibili slowly declined after mid-century.
Allegedly, but improbably, from the end of the 9th century, the principality of Capua claimed Gaeta as a courtesy title for the younger son of its ruling prince. In the mid-10th century, the De Ceremoniis of Constantine VII Porphyrogenitus lists the ceremonial title "prince of Gaeta" among the protocols for letters written to foreigners.
Prince Pandulf IV of Capua captured Gaeta in 1032 and deposed Duke John V, assuming the ducal and consular titles. In 1038, Prince Guaimar IV of Salerno took it from him and, in 1041, established the Norman counts of Aversa, who were afterwards princes of Capua, as puppet dukes. The native dynasty made a last attempt to wrest the
