Robert (son of William I of Sicily) explained

Robert (1153/4–1159/60) was the second son of King William I of Sicily and his queen, Margaret of Navarre. He was about four or five years old when he was appointed Prince of Capua in 1157 or 1158.^[1] Prior to his accession, since 1144, his father had been Prince of Capua. Robert's Latin title, princeps Capuanorum, means literally "Prince of Capuans".^[2] He was the third Robert of Capua, after Robert I and Robert II. The latter, who had been deposed in 1135, returned in 1155–56 in an effort to reclaim his principality. He managed to control some territory, but was ultimately unsuccessful.^[3] The young Robert's rule in Capua can be traced in documents between September 1158 and May 1159, but he had died by February–March 1160, when his father was once again ruling Capua directly.^[4] Eventually, Robert's younger brother Henry was appointed Prince of Capua in May 1166.^{[3] [2]}

Notes and References

1. 1157 is the implication of Hugo Falcandus, while Evelyn Jamison (1913), "The Norman Administration of Apulia and Capua, more especially under Roger II and William I, 1127–66", Papers of the British School at Rome 6: 281, derives a date of 1158, from two charters of dated to Indiction VII, March and July 1159, in of the eighth year of William's reign, which is also described as "the second year of the princeship of our lord Robert, by the grace of God the most glorious prince of the Capuans, and himself our lord king's son" (secundo anno principatus domini nostri Robberti dei gratia capuanorum Gloriosissimi principis, et ejusdem domini nostri Regis filii).
2. Hiroshi Takayama, The Administration of the Norman Kingdom of Sicily (E. J. Brill, 1993), p. 104.
3. Donald Matthew, The Norman Kingdom of Sicily (Cambridge University Press, 1992), p. 166.
4. G. A. Loud and Thomas E. J. Wiedemann, edd., The History of the Tyrants of Sicily by ‘Hugo Falcandus’, 1154–69 (Manchester University Press, 1998), p. 226.