Today is the feast of St. Cædwalla, King of the West Saxons, a son of Kinebert, and a great-grandson of Ceawlin. He was born about 659.
In 685, after a time in exile, during which he devastated Sussex, he began "to strive for the kingdom". His advisor, Bishop Wilfrid, "may not have been disinclined to help him".
A Dictionary of Christian Biography,  by William Smith and Henry Wace, Little, Brown, and Company, 1877.
"Within a couple of years Cædwalla had taken control of all the other provinces south of the Thames and established himself as ruler of the South Saxons, Surrey, and the Jutish provinces in Hampshire and the Isle of Wight. He made his brother Mul king of Kent, but Mul was burnt to death by the men of Kent in 687. Bede does not seek to hide the brutality which accompanied Cædwalla's conquests; the males of the royal house of Wight were hounded and put to death, and the subject provinces ravaged and made to pay a crippling tribute."
Kings and Kingdoms of Early Anglo-Saxon England,  by Barbara Yorke, Routledge, 1997.
In 689, Cædwalla, probably dying from wounds received in the battles at Wight, traveled to Rome. He was baptized at the shrine of St. Peter by Pope St. Sergius I, who became his godfather and gave him the name Petrus. He died a few days later, still wearing the white garments of baptism.
Cædwalla/Petrus was buried in St. Peter's. Click here  to read, in Bede's Ecclesiastical History of England, the lengthy epitaph written by Crispus, Archbishop of Milan, that was inscribed on the tombstone. When the old church was demolished in the 16th century to make way for the new St. Peter's Basilica, the tombstone was found, but since then, it has disappeared again.
Because of the successful advances of Ceawlin and his descendants, Cædwalla, Ine, and Alfred, the "West Saxon rulers became the kings of England."